Photosensitive composition, pattern-forming method using the photosensitive composition and compounds used in the photosensitive composition

ABSTRACT

A photosensitive composition containing a compound having a specific structure, a pattern-forming method using the photosensitive composition, and a compound having a specific structure used in the photosensitive composition.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photosensitive composition capable ofchanging the property by reaction upon irradiation with actinic ray orradiation, a pattern-forming method using the photosensitivecomposition, and the compounds used in the photosensitive composition.More specifically, the invention relates to a photosensitive compositionfor use in a manufacturing process of semiconductors, e.g., IC, themanufacture of circuit substrates for liquid crystals, thermal heads andthe like, and other photo-fabrication processes, lithographic printingplates, and acid-hardening compositions, and also the invention relatesto a pattern-forming process using the photosensitive composition, andthe compounds used in the photosensitive composition.

2. Description of the Related Art

Chemical amplification resist compositions are pattern-forming materialscapable of generating an acid at the area irradiated with actinic raysuch as a far ultraviolet ray or radiation, changing the solubility in adeveloper of the irradiated area with the actinic ray or radiation andthe solubility of the non-irradiated area by the reaction with the acidas a catalyst, and forming a pattern on a substrate.

When a KrF excimer laser is used as the exposure light source, resinshaving poly(hydroxystyrene) that is small in absorption in the region of248 nm as a fundamental skeleton are mainly used, so that a highsensitivity, high resolution and good pattern is formed as compared withconventionally used naphthoquinonediazide/novolak resins.

On the other hand, when a light source of further shorter wavelength,e.g., an ArF excimer laser (193 nm), is used as the exposure lightsource, since compounds having an aromatic group substantially showlarge absorption in the region of 193 nm, resists containing a resinhaving a highly transparent alicyclic hydrocarbon structure have beendeveloped for an ArF excimer laser.

Various compounds have been found as to acid generators that are mainconstitutional components of chemical amplification resists, e.g.,triaryl sulfonium salts and arylalkyl sulfonium salts are reported(e.g., refer to JP-A-2000-275845 and JP-A-10-48814).

As generating acids, e.g., in JP-A-2002-131897 and JP-A-2003-149812,specific fluorinated organic sulfonic acids are used. In JP-T-11-501909(The term “JP-T” as used herein refers to a “published Japanesetranslation of a PCT application”.), JP-A-2002-268223 andJP-A-2003-246786, imido anion acid generators capable of generatinghighly acidic imido upon irradiation with actinic ray or radiation areused.

However, these compounds are still insufficient in various points andthe improvement in line edge roughness, pattern profile and the like isrequired.

In the optical microscope, as a technique of enhancing resolution, amethod of filling in between a projection lens and a sample with aliquid having a high refractive index (hereinafter referred to as“immersion liquid”), i.e., an immersion method is conventionally known.

As “the effect of immersion”, resolution and the depth of focus can beexpressed by the following expressions in the case of immersion, with λ₀as the wavelength of the exposure light in the air, n as the refractiveindex of immersion liquid to the air, and NA₀=sin θ with θ asconvergence half angle of the ray of light:Resolution=k ₁·(λ₀ /n)/NA ₀Depth of focus=±k ₂·(λ₀ /n)/NA ₀ ²

That is, the effect of immersion is equivalent to the case of usingexposure wavelength of the wavelength of 1/n. In other words, in thecase of the projection optical system of the same NA, the depth of focuscan be made n magnifications by immersion. This is effective for everypattern form, and further, it is possible to combine an immersion methodwith super resolution techniques such as a phase shift method and atransformation lighting method now under discussion.

The example of the apparatus applying this effect to the transfer of amicro-fine image pattern of a semiconductor element are introduced inJP-A-57-153433 (the term “JP-A” as used herein refers to an “unexaminedpublished Japanese patent application”) and JP-A-7-220990.

The latest technical advancement of immersion exposure is reported inSPIE Proc., 4688, 11 (2002), J. Vac. Sci. Tecnol. B, 17 (1999), SPIEProc., 3999, 2 (2000), and WO 2004/077158. When an ArF excimer laser isused as the light source, it is thought that pure water (having arefractive index of 1.44 at 193 nm) is most promising as the immersionliquid in the light of the safety in handling, the transmittance and therefractive index at 193 nm. When an F2 excimer laser is used as thelight source, a solution containing fluorine is discussed from thebalance of the transmittance and the refractive index at 157 nm, but asufficiently satisfactory solution from the viewpoint of theenvironmental safety and at the point of refractive index has not beenfound yet. From the extent of the effect of immersion and the degree ofcompletion of resist, it is thought that immersion exposure techniquewill be carried on an ArF exposure apparatus earliest.

It is appointed that when a chemical amplification resist is applied toimmersion exposure, the resist layer is brought into contact with theimmersion liquid at the time of exposure, so that the resist layerdecomposes and ingredients that adversely influence the immersion liquidooze from the resist layer. WO 2004/068242 discloses that resistperformance decomposes by the immersion of a resist for ArF exposure inwater before and after exposure and appoints this is a problem inimmersion exposure.

SUMMARY OF THE INVENTION

An object of the invention is to provide a photosensitive compositionthat shows good line edge roughness and pattern profile, and improved inthe contrast of sensitivity and dissolution in EUV exposure. Anotherobject is to provide a pattern-forming method using the photosensitivecomposition. A further object is to provide compounds for use in thephotosensitive composition. Still further objects of the invention areto provide a photosensitive composition suitable for immersion exposurehaving good performances as described above even in immersion exposure,to provide a pattern-forming method using the photosensitivecomposition, and to provide compounds for use in the photosensitivecomposition.

The present invention is as follows.

(1) A photosensitive composition, which comprises (A) a sulfonium saltcompound represented by formula (I):

wherein A represents an (m+1)-valent linking group, when a plurality ofA's are present, the plurality of A's may be the same or different, andthe plurality of A's may be bonded to each other to form a cyclicstructure;

R represents a monovalent organic group, when two R's are present, thetwo R's may be the same or different, and the two R's may be bonded toeach other to form a cyclic structure;

L represents a lactone ring structure, when a plurality of L's arepresent, the plurality of L's may be the same or different;

X⁻ represents an anion;

n represents an integer of from 1 to 3; and

m represents an integer of 1 or 2.

(2) The photosensitive composition as described in (1) above,

wherein the (m+1)-valent linking group represented by A has an aromaticring.

(3) The photosensitive composition as described in (1) or (2) above,

wherein the anion represented by X⁻ in formula (I) is an organicsulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion (R¹—CO₂ ⁻), anorganic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)(CO—R¹)) or an organicmethidate anion (C⁻(SO₂—R¹)₃), wherein R¹ represents a monovalentorganic group.

(4) A pattern-forming method, which comprises:

forming a photosensitive film with a photosensitive composition asdescribed in any of (1) to (3) above; and

exposing and developing the photosensitive film.

(5) A compound, which is represented by formula (I):

wherein A represents an (m+1)-valent linking group, when a plurality ofA's are present, the plurality of A's may be the same or different, andthe plurality of A's may be bonded to each other to form a cyclicstructure;

R represents a monovalent organic group, when two R's are present, thetwo R's may be the same or different, and the two R's may be bonded toeach other to form a cyclic structure;

L represents a lactone ring structure, when a plurality of L's arepresent, the plurality of L's may be the same or different;

X⁻ represents an anion;

n represents an integer of from 1 to 3; and

m represents an integer of 1 or 2.

As preferred embodiments of the invention, the following constitutionsare exemplified.

(6) The photosensitive composition as described in any of (1) to (3)above, which further comprises (B) a compound capable of generating anacid upon irradiation with actinic ray or radiation.

(7) The photosensitive composition as described in (6) above,

wherein the compound of component (B) is a sulfonium salt of afluoro-substituted alkanesulfonic acid, a fluorine-substitutedbenzenesulfonic acid or a fluorine-substituted imidic acid.

(8) The positive photosensitive composition as described in any of (1)to (3), (6) and (7) above, which further comprises (C) a resin capableof decomposing by an action of an acid to increase solubility in analkali developing solution.

(9) The positive photosensitive composition as described in (8) above,

wherein the resin of component (C) has a fluorine atom on a main chainor side chain.

(10) The positive photosensitive composition as described in (8) above,

wherein the resin of component (C) has a hexafluoroisopropanolstructure.

(11) The positive photosensitive composition as described in (8) above,

wherein the resin of component (C) has a hydroxystyrene structural unit.

(12) The positive photosensitive composition as described in (8) above,

wherein the resin of component (C) has at least one repeating unitselected from 2-alkyl-2-adamantyl(meth)acrylate anddialkyl(1-adamantyl)methyl(meth)acrylate.

(13) The positive photosensitive composition as described in (8) above,

wherein the resin of component (C) has a monocyclic or polycyclicalicyclic hydrocarbon structure.

(14) The positive photosensitive composition as described in (13) above,

wherein the resin of component (C) has at least one repeating unitselected from 2-alkyl-2-adamantyl(meth)acrylate anddialkyl(1-adamantyl)methyl(meth)acrylate, at least one repeating unithaving a lactone structure and at least one repeating unit having ahydroxyl group.

(15) The positive photosensitive composition as described in (14) above,

wherein the resin of component (C) further has a repeating unit having acarboxyl group.

(16) The positive photosensitive composition as described in (8) above,

wherein the resin of component (C) has a silicon atom on a main chain orside chain.

(17) The positive photosensitive composition as described in (8) above,

wherein the resin of component (C) has a repeating unit having a lactonestructure.

(18) The positive photosensitive composition as described in any of (8)to (17) above, which further comprises (D) a dissolution inhibitingcompound capable of decomposing by an action of an acid to increasesolubility in an alkali developing solution and having a molecularweight of 3,000 or less.

(19) The positive photosensitive composition as described in any (1) to(3), (6) and, (7) above, which further comprises (E) a resin soluble inan alkali developing solution and (D) a dissolution inhibiting compoundcapable of decomposing by an action of an acid to increase solubility inan alkali developing solution and having a molecular weight of 3,000 orless.

(20) The negative photosensitive composition as described in any of (1)to (3), (6) and (7) above, which further comprises (E) a resin solublein an alkali developing solution and (F) an acid crosslinking agentcapable of crosslinking with the resin soluble in an alkali developingsolution by an action of an acid.

(21) The photosensitive composition as described in any of (1) to (3)and (6) to (20) above, which further comprises at least one of (G) abasic compound and (H) a fluorine and/or silicon surfactant.

(22) The photosensitive composition as described in (21) above,

wherein the basic compound (G) is a compound having a structure selectedfrom an imidazole structure, a diazabicyclo structure, an oniumhydroxide structure, an onium carboxylate structure, a trialkylaminestructure, an aniline structure and a pyridine structure, an alkylaminederivative having at least one of a hydroxyl group and an ether bond oran aniline derivative having at least one of a hydroxyl group and anether bond.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described in detail below.

In the description of a group (an atomic group) in the specification ofthe invention, the description not referring to substitution orunsubstitution includes both a group not having a substituent and agroup having a substituent. For example, “an alkyl group” includes notonly an alkyl group having no substituent (an unsubstituted alkyl group)but also an alkyl group having a substituent (a substituted alkylgroup).

A positive photosensitive composition in the invention, preferably apositive resist composition, contains (A) a sulfonium salt compoundrepresented by formula (I), and (C) a resin capable of decomposing bythe action of an acid to increase solubility in an alkali developingsolution, and if necessary, further contains (B) a compound capable ofgenerating an acid upon irradiation with actinic ray or radiation, and(D) a dissolution inhibiting compound capable of decomposing by theaction of an acid to increase solubility in an alkali developingsolution having a molecular weight of 3,000 or less, alternatively,contains (A) a sulfonium salt compound represented by formula (I), (E) aresin soluble in an alkali developing solution, and (D) a dissolutioninhibiting compound capable of decomposing by the action of an acid toincrease solubility in an alkali developing solution having a molecularweight of 3,000 or less, and if necessary, further contains (B) acompound capable of generating an acid upon irradiation with actinic rayor radiation.

A negative photosensitive composition in the invention, preferably anegative resist composition, contains (A) a sulfonium salt compoundrepresented by formula (I), (E) a resin soluble in an alkali developingsolution, and (F) an acid crosslinking agent capable of crosslinkingwith the resin soluble in an alkali developing solution by the action ofan acid, and if necessary, further contains (B) a compound capable ofgenerating an acid upon irradiation with actinic ray or radiation.

[1] (A) A sulfonium salt compound represented by formula (I):

A photosensitive composition in the invention contains a sulfonium saltcompound represented by the following formula (I) (also referred to as“compound (A)”).

In formula (I), A represents an (m+1)-valent linking group, when aplurality of A's are present, the plurality of A's may be the same ordifferent, and they may be bonded to each other to form a cyclicstructure; R represents a monovalent organic group, when two R's arepresent, the two R's may be the same or different, and they may bebonded to each other to form a cyclic structure; L represents a lactonering structure, when a plurality of L's are present, the plurality ofL's may be the same or different; X⁻ represents an anion; n representsan integer of from 1 to 3; and m represents an integer of 1 or 2.

Compound (A) is a compound capable of generating an acid uponirradiation with actinic ray or radiation.

The (m+1)-valent linking group represented by A in formula (I) is alinking group for linking S⁺ and L.

When m is 1, A represents a divalent linking group for linking S⁺ and L,and divalent groups, e.g., an arylene group, an alkylene group, acycloalkylene group, an alkenylene group, an ether group, an estergroup, etc., and divalent groups obtained by combining these groups canbe exemplified, and these groups may have a substituent.

As the arylene group, an arylene group having from 6 to 15 carbon atomsis preferred, e.g., a phenylene group, a naphthylene group, etc., can beexemplified.

As the alkylene group, a straight chain or branched alkylene grouphaving from 1 to 8 carbon atoms is preferred, e.g., a methylene group,an ethylene group, a propylene group, a butylene group, a hexylenegroup, an octylene group, etc., can be exemplified.

As the cycloalkylene group, a cycloalkylene group having from 5 to 12carbon atoms is preferred, e.g., a monocyclic residue such as acyclopentylene group, a cyclohexylene group, etc., and a polycyclicresidue such as a normornane skeleton, an adamantane skeleton, etc., canbe exemplified.

As the alkenylene group, an alkenylene group having from 2 to 6 carbonatoms is preferred, e.g., an ethenylene group, a propenylene group, abutenylene group, etc., can be exemplified.

When m is 2, A is a group using an arbitrary hydrogen atom in thedivalent linking group of the time of m being 1 as a hand for bonding toanother L.

The (m+1)-valent linking group represented by A has preferably 20 orless carbon atoms, and more preferably 15 or less carbon atoms.

It is preferred for the (m+1)-valent linking group represented by A tohave an aromatic ring, by which stability is improved, and thepreservation stability of the composition using this is improved. Thearomatic ring may be or may not be directly bonded to the sulfur atom(S⁺). As the aromatic ring, an aromatic ring having from 1 to 30 carbonatoms is preferred, e.g., a benzene ring, a naphthalene ring, ananthracene ring, a phenanthrene ring, a biphenylene ring, a fluorenering, a pyrene ring, etc., are exemplified. One or more aromatic ringsmay be bonded to one and the same A. As the aromatic ring, a benzenering, a naphthalene ring, and an anthracene ring are especiallypreferred, and the solubility in a solvent is improved by using thesearomatic rings.

The arylene group, alkylene group, cycloalkylene group, and alkenylenegroup as the (m+1)-valent linking group represented by A may besubstituted with one or more organic groups (B).

As the examples of organic groups (B), e.g., an alkyl group, acycloalkyl group, an aryl group, an aralkyl group, an alkenyl group, analkoxyl group, an alkoxycarbonylamino group, an alkylthio group, analkyliminosulfonyl group, a cycloalkylaryloxysulfonyl group, a cyanogroup, etc., can be exemplified. When a plurality of organic groups (B)are present, the plurality of organic groups (B) may be the same ordifferent.

The alkyl group as organic group (B) may have a substituent. The alkylgroup is preferably a straight chain or branched alkyl group having from1 to 30 carbon atoms, and an oxygen atom, a sulfur atom or a nitrogenatom may be contained in the alkyl chain. Specifically, a straight chainalkyl group, e.g., a methyl group, an ethyl group, an n-propyl group, ann-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, ann-dodecyl group, an n-tetradecyl group, an n-octadecyl group, etc., anda branched alkyl group, e.g., an isopropyl group, an isobutyl group, at-butyl group, a neopentyl group, a 2-ethylhexyl group, etc., can beexemplified.

The cycloalkyl group as organic group (B) may have a substituent. Thecycloalkyl group is preferably a cycloalkyl group having from 3 to 20carbon atoms, and an oxygen atom may be contained in the ring.Specifically, a cyclopropyl group, a cyclopentyl group, a cyclohexylgroup, a norbornyl group, an adamantyl group, etc., can be exemplified.

The aryl group as organic group (B) may have a substituent. The arylgroup is preferably an aryl group having from 6 to 14 carbon atoms,e.g., a phenyl group, a naphthyl group, etc., can be exemplified.

The aralkyl group as organic group (B) may have a substituent. Thearalkyl group is preferably an aralkyl group having from 7 to 20 carbonatoms, e.g., a benzyl group, a phenethyl group, a naphthylmethyl group,and a naphthylethyl group can be exemplified.

As the alkenyl group as organic group (B), a group having a double bondon an arbitrary position of the above alkyl group can be exemplified.

The alkoxyl group, and the alkoxyl group in the alkoxycarbonylaminogroup as organic group (B) is preferably an alkoxyl group having from 1to 30 carbon atoms, e.g., a methoxy group, an ethoxy group, a propoxygroup, an n-butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, etc., can be exemplified.

As the alkyl group in the alkylthio group and the alkyliminosulfonylgroup as organic group (B), the above alkyl group can be exemplified.

As the cycloalkyl group and the aryl group in thecycloalkylaryloxysulfonyl group as organic group (B), the abovecycloalkyl group and the aryl group can be exemplified.

As further substituents that each of the above organic groups (B) mayhave, e.g., a halogen atom, a hydroxyl group, a nitro group, a cyanogroup, a carboxyl group, a carbonyl group, a cycloalkyl group(preferably having from 3 to 10 carbon atoms), an aryl group (preferablyhaving from 6 to 14 carbon atoms), an alkoxyl group (preferably havingfrom 1 to 10 carbon atoms), an acyl group (preferably having from 2 to20 carbon atoms), an acyloxy group (preferably having from 2 to 10carbon atoms), an alkoxycarbonyl group (preferably having from 2 to 20carbon atoms), an aminoacyl group (preferably having from 2 to 10 carbonatoms), etc., can be exemplified. As a further substituent in connectionwith the cyclic structure in the aryl group and the cycloalkyl group, analkyl group (preferably having from 1 to 10 carbon atoms) can beexemplified. As a further substituent in regard to the aminoacyl group,an alkyl group having 1 or 2 carbon atoms (preferably from 1 to 10) canbe exemplified.

The (m+1)-valent linking group represented by A may further besubstituted with a halogen atom (preferably a fluorine atom), etc.

As the monovalent organic group represented by R, e.g., an alkyl group,a cycloalkyl group, an aryl group, an aralkyl group, an alkenyl group,etc., can be exemplified.

The alkyl group as the monovalent organic group represented by R mayhave a substituent. The alkyl group is preferably a straight chain orbranched alkyl group having from 1 to 30 carbon atoms, and an oxygenatom, a sulfur atom, or a nitrogen atom may be contained in the alkylchain. Specifically, a straight chain alkyl group, e.g., a methyl group,an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group,an n-hexyl group, an n-octyl group, an n-dodecyl group, an n-tetradecylgroup, an n-octadecyl group, etc., and a branched alkyl group, e.g., anisopropyl group, an isobutyl group, a t-butyl group, a neopentyl group,a 2-ethylhexyl group, etc., can be exemplified.

The cycloalkyl group as the monovalent organic group represented by Rmay have a substituent. The cycloalkyl group is preferably a cycloalkylgroup having from 3 to 20 carbon atoms, and an oxygen atom may becontained in the ring. Specifically, a cyclopropyl group, a cyclopentylgroup, a cyclohexyl group, a norbornyl group, an adamantyl group, etc.,can be exemplified.

The aryl group as the monovalent organic group represented by R may havea substituent. The aryl group is preferably an aryl group having from 6to 14 carbon atoms and, e.g., a phenyl group, a naphthyl group, etc.,can be exemplified.

The aralkyl group as the monovalent organic group represented by R mayhave a substituent. The aralkyl group is preferably an aralkyl grouphaving from 7 to 20 carbon atoms and, e.g., a benzyl group, a phenethylgroup, a naphthylmethyl group, and a naphthylethyl group can beexemplified.

As the alkenyl group as the monovalent organic group represented by R, agroup having a double bond on an arbitrary position of the above alkylgroup can be exemplified.

As further substituents that the monovalent organic groups representedby R may have, e.g., a halogen atom, a hydroxyl group, a nitro group, acyano group, a carboxyl group, a carbonyl group, a cycloalkyl group(preferably having from 3 to 10 carbon atoms), an aryl group (preferablyhaving from 6 to 14 carbon atoms), an alkoxyl group (preferably havingfrom 1 to 10 carbon atoms), an acyl group (preferably having from 2 to20 carbon atoms), an acyloxy group (preferably having from 2 to 10carbon atoms), an alkoxycarbonyl group (preferably having from 2 to 20carbon atoms), an aminoacyl group (preferably having from 2 to 10 carbonatoms), etc., can be exemplified. As a further substituent in connectionwith the cyclic structure in the aryl group and cycloalkyl group, analkyl group (preferably having from 1 to 10 carbon atoms) can beexemplified. As a further substituent in regard to the aminoacyl group,an alkyl group having 1 or 2 carbon atoms (preferably from 1 to 10) canbe exemplified.

The number of carbon atoms constituting the lactone ring structurerepresented by L is preferably from 4 to 20, and more preferably from 4to 10. The lactone ring structure represented by L may be substitutedwith one or more organic groups (B).

The lactone ring structure represented by L is preferably a 5- to7-membered lactone structure, and other ring structures may be condensedwith the 5- to 7-membered lactone structure to form a bicyclo structureor spiro structure. The lactone ring structures represented by any ofthe following formulae (LC1-1) to (LC1-16) are more preferred.Especially preferred lactone ring structures are (LC1-1), (LC1-4),(LC1-5), (LC1-6), (LC1-13) and (LC1-14). By the use of a specificlactone ring structure, development defect is bettered.

The lactone ring structure may have or may not have a substituent (Rb₂).As preferred substituent (Rb₂), an alkyl group having from 1 to 8 carbonatoms, a cycloalkyl group having from 3 to 7 carbon atoms, an alkoxylgroup having from 1 to 8 carbon atoms, an alkoxycarbonyl group havingfrom 1 to 8 carbon atoms, a carboxyl group, a halogen atom, a hydroxylgroup, a cyano group, and an acid-decomposable group are exemplified. n₂represents an integer of from 0 to 4. When n₂ is 2 or more, a pluralityof Rb₂ may be the same or different, and the plurality of Rb₂ may bebonded to each other to form a ring.

It is sufficient for the lactone ring structure represented by L to bebonded to the linking group represented by A on an arbitrary position ofthe ring.

The specific examples of the cationic parts in compound (A) are shownbelow, but the invention is not restricted thereto.

As the anions represented by X⁻ in formula (I), for example, an organicsulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion (R¹—CO₂ ⁻), anorganic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)(CO—R¹)), an organicmethidate anion (C⁻(SO₂—R¹)₃), a halogen anion (Br⁻, Cl⁻), BF₄ ⁻, andPF₆ ⁻ are exemplified. As the anions represented by X⁻, an organicsulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion (R¹—CO₂ ⁻), anorganic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)—(CO—R¹)), an organicmethidate anion (C⁻(SO₂—R¹)₃) are especially preferred. Here, R¹represents a monovalent organic group.

The monovalent organic group represented by R¹ preferably has from 1 to40 carbon atoms and, e.g., an alkyl group, an aryl group and a camphorresidue can be exemplified. A plurality of R¹ may be the same ordifferent, may be bonded to each other to form a ring, or may besubstituted with a halogen atom (preferably a fluorine atom) or theabove organic group (B).

The alkyl group represented by R¹ is preferably a straight chain orbranched alkyl group having from 1 to 30 carbon atoms, and two or moreof an oxygen atom, a sulfur atom, a sulfur atom added with an oxygenatom, and nitrogen atom may be contained in the alkyl chain.Specifically as R¹, a straight chain alkyl group, e.g., a methyl group,an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group,an n-hexyl group, an n-octyl group, an n-dodecyl group, an n-tetradecylgroup, an n-octadecyl group, etc., and a branched alkyl group, e.g., anisopropyl group, an isobutyl group, a t-butyl group, a neopentyl group,a 2-ethylhexyl group, etc., can be exemplified. By substituting from 30to 100% of the hydrogen atoms of the alkyl group with fluorine atoms,heat stability is improved, so that more preferred. As the alkyl groupssubstituted with a fluorine atom, perfluoroalkyl groups, e.g., aperfluoro-methyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluorobutyl group, etc., can be exemplified.

The aryl group represented by R¹ may have a substituent. The aryl groupis preferably an aryl group having from 6 to 14 carbon atoms and, e.g.,a phenyl group, a naphthyl group, etc., can be exemplified. It ispreferred that the aryl group is substituted with a fluorine atom. Asthe aryl group substituted with a fluorine atom, a perfluorophenyl groupcan be exemplified.

The specific examples of the anionic parts in compound (A) are shownbelow, but the invention is not restricted thereto.

The specific examples of compound (A) are shown in Table 1 below, butthe invention is not restricted thereto.

TABLE 1 Anionic Part Compound (A) Cationic Part (X⁻) A-1 I-1 X4 A-2 I-1X3 A-3 I-1 X2 A-4 I-2 X4 A-5 I-3 X4 A-6 I-3 X3 A-7 I-3 X2 A-8 I-4 X5 A-9I-5 X4 A-10 I-6 X4 A-11 I-7 X3 A-12 I-8 X4 A-13 I-9 X16 A-14 I-10 X4A-15 I-11 X6 A-16 I-12 X7 A-17 I-13 X4 A-18 I-14 X4 A-19 I-15 X12 A-20I-16 X4 A-21 I-17 X3 A-22 I-18 X4 A-23 I-19 X4 A-24 I-20 X11 A-25 I-21X4 A-26 I-22 X3 A-27 I-23 X4 A-28 I-24 X3 A-29 I-25 X4 A-30 I-26 X3 A-31I-26 X3 A-32 I-27 X4 A-33 I-27 X14 A-34 I-28 X4 A-35 I-28 X17 A-36 I-28X3 A-37 I-28 X15 A-38 I-28 X13 A-39 I-29 X4 A-40 I-30 X4 A-41 I-31 X4A-42 I-32 X10 A-43 I-33 X4 A-44 I-34 X15 A-45 I-35 X4 A-46 I-36 X4 A-47I-37 X3 A-48 I-38 X4 A-49 I-39 X4 A-50 I-40 X3 A-51 I-41 X4 A-52 I-42 X3A-53 I-43 X4 A-54 I-44 X9 A-55 I-45 X4 A-56 I-46 X3 A-57 I-47 X4 A-58I-48 X14 A-59 I-49 X11 A-60 I-50 X4 A-61 I-51 X16 A-62 I-52 X4 A-63 I-53X4 A-64 I-54 X3 A-65 I-55 X3 A-66 I-56 X16 A-67 I-57 X2

Compound (A) is a novel compound.

Compound (A) can be synthesized by the reaction of a sulfonium compoundhaving a hydroxyl group that is easily available and capable of beingsynthesized and a compound having a lactone structure to which aseparable group (e.g., a halogen atom) is introduced according toWilliamson's synthesis method (the following scheme 1).

A sulfonium skeleton can be formed by the reaction of a diphenylsulfoxide derivative and an aryl compound having a lactone structureunder an acidic condition or in the presence of an activating agent suchas an acid anhydride (refer to JP-A-2002-193925, the following scheme2).

The content of compound (A) in the photosensitive composition of theinvention is preferably from 0.1 to 20 mass % based on the solidscontent of the composition, and more preferably from 0.1 to 10 mass %.(In this specification, mass ratio is equal to weight ratio.)

[2] (B) A compound capable of generating an acid upon irradiation withactinic ray or radiation:

It is preferred for the photosensitive composition in the invention tofurther contain a compound capable of generating an acid uponirradiation with actinic ray or radiation (hereinafter also referred toas “an acid generator usable in combination”) besides compound (A).

As acid generators usable in combination, photocationic polymerizationphotoinitiators, photoradical polymerization photoinitiators,photo-decoloring agents, photo-discoloring agents of dyestuffs, knowncompounds capable of generating an acid upon irradiation with actinicray or radiation that are used in micro-resists and the like, and themixtures of these compounds can be optionally selected and used.

For example, diazonium salt, phosphonium salt, sulfonium salt, iodoniumsalt, imidosulfonate, oximesulfonate, diazodisulfone, disulfone, ando-nitrobenzylsulfonate are exemplified as acid generators usable incombination.

Further, compounds obtained by introducing a group or a compound capableof generating an acid upon irradiation with actinic ray or radiation tothe main chain or side chain of polymers, for example, the compoundsdisclosed in U.S. Pat. No. 3,849,137, German Patent 3,914,407,JP-A-63-26653, JP-A-55-164824, JP-A-62-69263, JP-A-63-146038,JP-A-63-163452, JP-A-62-153853, JP-A-63-146029, etc., can be used.

The compounds capable of generating an acid by the action of lights asdisclosed in U.S. Pat. No. 3,779,778, EP 126712, etc., can also be used.

As preferred acid generators usable in combination, compoundsrepresented by the following formula (ZI), (ZII) or (ZIII) can beexemplified.

In formula (ZI), R₂₀₁, R₂₀₂ and R₂₀₃ each represents an organic group.

The number of carbon atoms of the organic groups represented by R₂₀₁,R₂₀₂ and R₂₀₃ is generally from 1 to 30, and preferably from 1 to 20.

Two of R₂₀₁, R₂₀₂ and R₂₀₃ may be bonded to each other to form a cyclicstructure, and an oxygen atom, a sulfur atom, an ester bond, an amidobond or a carbonyl group may be contained in the ring. As the groupformed by bonding two of R₂₀₀, R₂₀₂ and R₂₀₃, an alkylene group (e.g., abutylene group, a pentylene group) can be exemplified.

Z⁻ represents a non-nucleophilic anion.

The examples of the non-nucleophilic anions represented by Z⁻ include,e.g., a sulfonate anion, a carboxylate anion, a sulfonylimide anion, abis(alkylsulfonyl)imide anion, and a tris(alkylsulfonyl)methyl anion.

A non-nucleophilic anion is an anion having extremely low ability ofcausing a nucleophilic reaction and capable of restraining the agingdecomposition due to an intramolecular nucleophilic reaction, so thatthe aging stability of a resist can be improved with a non-nucleophilicanion.

As the sulfonate anion, e.g., an aliphatic sulfonate anion, an aromaticsulfonate anion and a camphor sulfonate anion are exemplified.

As the carboxylate anion, e.g., an aliphatic carboxylate anion, anaromatic carboxylate anion and an aralkylcarboxylate anion areexemplified.

The aliphatic moiety in the aliphatic sulfonate anion may be an alkylgroup or a cycloalkyl group, preferably an alkyl group having from 1 to30 carbon atoms and a cycloalkyl group having from 3 to 30 carbon atoms,e.g., a methyl group, an ethyl group, a propyl group, an isopropylgroup, an n-butyl group, an isobutyl group, a sec-butyl group, a pentylgroup, a neopentyl group, a hexyl group, a heptyl group, an octyl group,a nonyl group, a decyl group, an undecyl group, a dodecyl group, atridecyl group, a tetradecyl group, a pentadecyl group, a hexadecylgroup, a heptadecyl group, an octadecyl group, a nonadecyl group, aneicosyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexylgroup, an adamantyl group, a norbonyl group, a boronyl group, etc., areexemplified.

The aromatic group in the aromatic sulfonate anion is preferably an arylgroup having from 6 to 14 carbon atoms and, e.g., a phenyl group, atolyl group, a naphthyl group, etc., are exemplified.

The alkyl group, cycloalkyl group and aryl group in the aliphaticsulfonate anion and aromatic sulfonate anion may have a substituent. Asthe substituents of the alkyl group, cycloalkyl group and aryl group inthe aliphatic sulfonate anion and aromatic sulfonate anion, e.g., anitro group, a halogen atom (a fluorine atom, a chlorine atom, a bromineatom, and an iodine atom), a carboxyl group, a hydroxyl group, an aminogroup, a cyano group, an alkoxyl group (preferably having from 1 to 15carbon atoms), a cycloalkyl group (preferably having from 3 to 15 carbonatoms), an aryl group (preferably having from 6 to 14 carbon atoms), analkoxycarbonyl group (preferably having from 2 to 7 carbon atoms), anacyl group (preferably having from 2 to 12 carbon atoms), analkoxy-carbonyloxy group (preferably having from 2 to 7 carbon atoms),an alkylthio group (preferably having from 1 to 15 carbon atoms), analkylsulfonyl group (preferably having from 1 to 15 carbon atoms), analkyliminosulfonyl group (preferably having from 2 to 15 carbon atoms),an aryloxysulfonyl group (preferably having from 6 to 20 carbon atoms),an alkylaryloxysulfonyl group (preferably having from 7 to 20 carbonatoms), a cycloalkylaryloxysulfonyl group (preferably having from 10 to20 carbon atoms), an alkyloxyalkyloxy group (preferably having from 5 to20 carbon atoms), a cycloalkylalkyloxyalkyloxy group (preferably havingfrom 8 to 20 carbon atoms), etc., are exemplified. As for the aryl groupand the cyclic structure of each group, an alkyl group (preferablyhaving from 1 to 15 carbon atoms) can be further exemplified as thesubstituent.

As the aliphatic moiety in the aliphatic carboxylate anion, the samealkyl group and cycloalkyl group as in the aliphatic sulfonate anion canbe exemplified.

As the aromatic group in an aromatic carboxylate anion, the same arylgroup as in the aromatic sulfonate anion can be exemplified.

As the aralkyl group in the aralkylcarboxylate anion, preferably anaralkyl group having from 6 to 12 carbon atoms, e.g., a benzyl group, aphenethyl group, a naphthylmethyl group, a naphthylethyl group, anaphthylmethyl group, etc., can be exemplified.

The alkyl group, cycloalkyl group, aryl group and aralkyl group in thealiphatic carboxylate anion, aromatic carboxylate anion andaralkylcarboxylate anion may have a substituent. As the substituents ofthe alkyl group, cycloalkyl group, aryl group and aralkyl group in thealiphatic carboxylate anion, aromatic carboxylate anion andaralkylcarboxylate anion, e.g., the same halogen atom, alkyl group,cycloalkyl group, alkoxyl group, alkylthio group, etc., as in thearomatic sulfonate anion can be exemplified.

As the sulfonylimide anion, e.g., a saccharin anion can be exemplified.

The alkyl group in the bis(alkylsulfonyl)imide anion andtris(alkylsulfonyl)methyl anion is preferably an alkyl group having from1 to 5 carbon atoms and, e.g., a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, asec-butyl group, a pentyl group a neopentyl group, etc., areexemplified. As the substituents on these alkyl groups, a halogen atom,an alkyl group substituted with a halogen atom, an alkoxyl group, analkylthio group, an alkyloxysulfonyl group, an aryloxysulfonyl group, acycloalkylaryloxysulfonyl group, etc., can be exemplified, and an alkylgroup substituted with a fluorine atom is preferred.

As other non-nucleophilic anions, e.g., fluorinated phosphorus,fluorinated boron and fluorinated antimony can be exemplified.

As the non-nucleophilic anions represented by Z⁻, an aliphatic sulfonateanion in which the α-position of the sulfonic acid is substituted with afluorine atom, an aromatic sulfonate anion substituted with a fluorineatom or a group having a fluorine atom, a bis(alkylsulfonyl)imide anionin which the alkyl group is substituted with a fluorine atom, and atris(alkylsulfonyl)methide anion in which the alkyl group is substitutedwith a fluorine atom are preferred. Especially preferrednon-nucleophilic anions are an aliphatic perfluoro-sulfonate anionhaving from 4 to 8 carbon atoms, and a benzenesulfonate anion having afluorine atom, and still more preferred non-nucleophilic anions are anonafluorobutane-sulfonate anion, a perfluorooctanesulfonate anion, apenta-fluorobenzenesulfonate anion, and a3,5-bis(trifluoro-methyl)benzenesulfonate anion.

As the examples of the organic groups represented by R₂₀₁, R₂₀₂ andR₂₀₃, the corresponding groups in the later-described compoundsrepresented by formula (ZI-1), (ZI-2) or (ZI-3) can be exemplified.

The compound represented by formula (ZI) may be a compound having aplurality of structures represented by formula (ZI). For instance,compound (ZI) may be a compound having a structure that at least one ofR₂₀₁, R₂₀₂ and R₂₀₃ of the compound represented by formula (ZI) isbonded to at least one of R₂₀₁, R₂₀₂ and R₂₀₃ of another compoundrepresented by formula (ZI).

The following compounds (ZI-1), (ZI-2) and (ZI-3) can be exemplified asmore preferred components (ZI).

Compound (ZI-1) is an arylsulfonium compound in the case where at leastone of R₂₀₁ to R₂₀₃ in formula (ZI) represents an aryl group, i.e., acompound having arylsulfonium as a cation.

All of R₂₀₁ to R₂₀₃ of the arylsulfonium compound may be aryl groups, ora part of R₂₀₁ to R₂₀₃ is an aryl group and the remainder may be analkyl group or a cycloalkyl group.

As the arylsulfonium compounds, e.g., a triarylsulfonium compound, adiarylalkylsulfonium compound, an aryldialkyl-sulfonium compound, adiarylcycloalkylsulfonium compound, and an aryldicycloalkylsulfoniumcompound are exemplified.

As the aryl groups of the arylsulfonium compound, a phenyl group and anaphthyl group are preferred, and the more preferred aryl group is aphenyl group. The aryl group may be an aryl group having a heterocyclicstructure having an oxygen atom, a nitrogen atom or a sulfur atom. Asthe aryl group having a heterocyclic structure, e.g., a pyrrole residue(a group formed by eliminating one hydrogen atom from pyrrole), a furanresidue (a group formed by eliminating one hydrogen atom from furan), athiophene residue (a group formed by eliminating one hydrogen atom fromthiophene), an indole residue (a group formed by eliminating onehydrogen atom from indole), a benzofuran residue (a group formed byeliminating one hydrogen atom from benzofuran), and a benzothiopheneresidue (a group formed by eliminating one hydrogen atom frombenzothiophene) can be exemplified. When the arylsulfonium compound hastwo or more aryl groups, these two or more aryl groups may be the sameor different.

As the alkyl group or cycloalkyl group that the arylsulfonium compoundhas according to necessity, a straight chain or branched alkyl grouphaving from 1 to 15 carbon atoms and a cycloalkyl group having from 3 to15 carbon atoms are preferred, e.g., a methyl group, an ethyl group, apropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, acyclopropyl group, a cyclobutyl group, a cyclohexyl group, etc., can beexemplified.

The aryl group, alkyl group and cycloalkyl group represented by R₂₀₀,R₂₀₂ and R₂₀₃ may have a substituent and, e.g., an alkyl group (e.g.,having from 1 to 15 carbon atoms), a cycloalkyl group (e.g., having from3 to 15 carbon atoms), an aryl group (e.g., having from 6 to 14 carbonatoms), an alkoxyl group (e.g., having from 1 to 15 carbon atoms), ahalogen atom, a hydroxyl group, and a phenylthio group are exemplifiedas the substituents. The preferred substituents are a straight chain orbranched alkyl group having from 1 to 12 carbon atoms, a cycloalkylgroup having from 3 to 12 carbon atoms, and a straight chain, branchedor cyclic alkoxyl group having from 1 to 12 carbon atoms, and morepreferred substituents are an alkyl group having from 1 to 4 carbonatoms and an alkoxyl group having from 1 to 4 carbon atoms. Thesubstituent may be substituted on any one of three of R₂₀, to R₂₀₃, ormay be substituted on all of the three. When R₂₀₁, R₂₀₂ and R₂₀₃ eachrepresents an aryl group, it is preferred that the substituent besubstituted on the p-position of the aryl group.

Compound (ZI-2) is described below.

Compound (ZI-2) is a compound in the case where R₂₀₁, R₂₀₂ and R₂₀₃ informula (ZI) each represents an organic group not containing an aromaticring. The aromatic ring also includes an aromatic ring containing ahetero atom.

The organic groups not containing an aromatic ring represented by R₂₀₁to R₂₀₃ generally have from 1 to 30 carbon atoms, and preferably from 1to 20 carbon atoms.

R₂₀₁, R₂₀₂ and R₂₀₃ each preferably represents an alkyl group, acycloalkyl group, an allyl group, or a vinyl group, more preferably astraight chain or branched 2-oxoalkyl group, a 2-oxocycloalkyl group oran alkoxycarbonylmethyl group, and especially preferably a straight orbranched 2-oxoalkyl group.

The alkyl group and cycloalkyl group represented by R₂₀₁ to R₂₀₃ arepreferably a straight chain or branched alkyl group having from 1 to 10carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, abutyl group, a pentyl group), and a cycloalkyl group having from 3 to 10carbon atoms (e.g., a cyclopentyl group, a cyclohexyl group, a norbonylgroup). The alkyl group is more preferably a 2-oxoalkyl group or analkoxycarbonylmethyl group. The cycloalkyl group is more preferably a2-oxocycloalkyl group.

The 2-oxoalkyl group may be either a straight chain or branched group,and a group having >C═O on the 2-position of the above alkyl group canbe exemplified as a preferred group.

The 2-oxocycloalkyl group is preferably a group having >C═O on the2-position of the above cycloalkyl group.

As the alkoxyl group in the alkoxycarbonylmethyl group, an alkoxyl grouppreferably having from 1 to 5 carbon atoms (e.g., a methoxy group, anethoxy group, a propoxy group, a butoxy group, a pentoxy group) can beexemplified.

R₂₀₁ to R₂₀₃ may further be substituted with a halogen atom, an alkoxylgroup (e.g., having from 1 to 5 carbon atoms), a hydroxyl group, a cyanogroup, or a nitro group.

Compound (ZI-3) is a compound represented by the following formula(ZI-3), which compound has a phenacyl-sulfonium salt structure.

In formula (ZI-3), R_(1c), R_(2c), R_(3c), R_(4c) and R_(5c) eachrepresents a hydrogen atom, an alkyl group, a cycloalkyl group, analkoxy group, or a halogen atom.

R_(6c) and R_(7c) each represents a hydrogen atom, an alkyl group or acycloalkyl group.

R_(x) and R_(y) each represents an alkyl group, a cycloalkyl group, anallyl group, or a vinyl group.

Any two or more of R_(1c) to R_(5c), R_(6c) and R_(7c), and R_(x) andR_(y) may be bonded to each other to form cyclic structures,respectively, and the cyclic structures may contain an oxygen atom, asulfur atom, an ester bond, or an amido bond. As the groups formed byany two or more of R_(1c) to R_(5c), R_(6c) and R_(7c), and R_(x) andR_(y), a butylene group, a pentylene group, etc., can be exemplified.

Z_(c) ⁻ represents a non-nucleophilic anion, and the samenon-nucleophilic anions as represented by Z⁻ in formula (ZI) can beexemplified.

The alkyl groups represented by R_(1c) to R_(7c) may be either straightchain or branched, e.g., an alkyl group having from 1 to 20 carbonatoms, preferably a straight chain or branched alkyl group having from 1to 12 carbon atoms (e.g., a methyl group, an ethyl group, a straightchain or branched propyl group, a straight chain or branched butylgroup, a straight chain or branched pentyl group) can be exemplified. Asthe cycloalkyl groups represented by R_(1c) to R_(7c), a cycloalkylgroup having from 3 to 8 carbon atoms (e.g., a cyclopentyl group and acyclohexyl group) can be exemplified.

The alkoxyl groups represented by R_(1c) to R_(5c) may be any ofstraight chain, branched and cyclic, e.g., an alkoxyl group having from1 to 10 carbon atoms, preferably a straight chain or branched alkoxylgroup having from 1 to 5 carbon atoms (e.g., a methoxy group, an ethoxygroup, a straight chain or branched propoxy group, a straight chain orbranched butoxy group, a straight chain or branched pentoxy group), acyclic alkoxyl group having from 3 to 8 carbon atoms (e.g., acyclopentyloxy group, a cyclohexyloxy group) can be exemplified.

It is preferred that any of R_(1c) to R_(5c) represents a straight chainor branched alkyl group, a cycloalkyl group, or a straight chain,branched or cyclic alkoxyl group, it is more preferred that the sumtotal of the carbon atoms of R_(1c) to R_(5c) is from 2 to 15, by whichthe solubility in a solvent increases and generation of particles duringpreservation can be restrained.

As the alkyl group and cycloalkyl group represented by R_(x) and R_(y),the same alkyl groups and cycloalkyl groups as represented by R_(1c) toR_(7c) can be exemplified, and a 2-oxoalkyl group, a 2-oxocycloalkylgroup, and an alkoxycarbonylmethyl group are more preferred.

As the 2-oxoalkyl group and 2-oxocycloalkyl group, groups having >C═O onthe 2-position of the alkyl group and cycloalkyl group represented byR_(1c) to R_(7c) can be exemplified.

As the alkoxyl group in the alkoxycarbonylmethyl group, the same alkoxylgroups as those represented by R_(1c) to R_(5c) can be exemplified.

R_(x) and R_(y) each preferably represents an alkyl group or acycloalkyl group having 4 or more carbon atoms, more preferably 6 ormore carbon atoms, and still more preferably an alkyl group or acycloalkyl group having 8 or more carbon atoms.

In formulae (ZII) and (ZIII), R₂₀₄, R₂₀₅, R₂₀₆ and R₂₀₇ each representsan aryl group, an alkyl group, or a cycloalkyl group.

The aryl group represented by R₂₀₄ to R₂₀₇ is preferably a phenyl groupor a naphthyl group, and more preferably a phenyl group. The aryl grouprepresented by R₂₀₄ to R₂₀₇ may be an aryl group having a heterocyclicstructure having an oxygen atom, a nitrogen atom or a sulfur atom. Asthe aryl group having a heterocyclic structure, e.g., a pyrrole residue(a group formed by eliminating one hydrogen atom from pyrrole), a furanresidue (a group formed by eliminating one hydrogen atom from furan), athiophene residue (a group formed by eliminating one hydrogen atom fromthiophene), an indole residue (a group formed by eliminating onehydrogen atom from indole), a benzofuran residue (a group formed byeliminating one hydrogen atom from benzofuran), a benzothiophene residue(a group formed by eliminating one hydrogen atom from benzothiophene),etc., can be exemplified.

The alkyl group and cycloalkyl group represented by R₂₀₄ to R₂₀₇ arepreferably a straight chain or branched alkyl group having from 1 to 10carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, abutyl group, a pentyl group), and a cycloalkyl group having from 3 to 10carbon atoms (e.g., a cyclopentyl group, a cyclohexyl group, a norbonylgroup).

The aryl group, alkyl group and cycloalkyl group represented by R₂₀₄ toR₂₀₇ may have a substituent. As the substituents that the aryl group,alkyl group and cycloalkyl group represented by R₂₀₄ to R₂₀₇ may have,e.g., an alkyl group (e.g., having from 1 to 15 carbon atoms), acycloalkyl group (e.g., having from 3 to 15 carbon atoms), an aryl group(e.g., having from 6 to 15 carbon atoms), an alkoxyl group (e.g., havingfrom 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, and aphenylthio group can be exemplified.

Z⁻ represents a non-nucleophilic anion, and the same non-nucleophilicanions as those represented by Z⁻ in formula (ZI) can be exemplified.

As the acid generators usable in combination, the compounds representedby the following formula (ZIV), (ZV) or (ZVI) can further beexemplified.

In formulae (ZIV), (ZV) and (ZVI), Ar₃ and Ar₄ each represents an arylgroup.

R₂₀₆, R₂₀₇ and R₂₀₈ each represents an alkyl group, a cycloalkyl groupor an aryl group.

A represents an alkylene group, an alkenylene group or an arylene group.

Of the acid generators usable in combination, more preferred compoundsare the compounds represented by formulae (ZI), (ZII) and (ZIII).

Further, as the acid generators usable in combination, a compoundgenerating an acid having one sulfonic acid group or an imido group ispreferred, a compound generating a monovalent perfluoroalkanesulfonicacid, a compound generating an aromatic sulfonic acid substituted with amonovalent fluorine atom or a group containing a fluorine atom, and acompound generating an imidic acid substituted with a monovalentfluorine atom or a group containing a fluorine atom are more preferred,and a sulfonium salt of a fluorine-substituted alkanesulfonic acid, afluorine-substituted benzenesulfonic acid, or a fluorine-substitutedimidic acid is still more preferred. As the acid generators usable incombination, a fluorine-substituted alkanesulfonic acid, afluorine-substituted benzenesulfonic acid, and fluorine-substitutedimidic acid each having pKa of −1 or less of generated acid areespecially preferred, by which sensitivity is improved.

The examples of especially preferred acid generators usable incombination are shown below.

The acid generators usable in combination can be used alone, or two ormore in combination.

The content of the acid generators usable in combination in aphotosensitive composition is preferably from 0.1 to 20 mass % based onthe total solids content of the photosensitive composition, morepreferably from 0.5 to 10 mass %, and still more preferably from 1 to 7mass %.

[3] (C) A resin capable of decomposing by the action of an acid toincrease solubility in an alkali developing solution (referred to asalso component (C)):

A resin capable of decomposing by the action of an acid to increasesolubility in an alkali developing solution for use in the positivephotosensitive composition in the invention is a resin having a groupdecomposable by the action of an acid (hereinafter referred to as “anacid-decomposable group”) on the main chain or side chain of the resin,or on both the main chain and side chain. A resin having a groupdecomposable by the action of an acid on the side chain is morepreferred.

A preferred acid-decomposable group is a group obtained by substitutingthe hydrogen atom of a —COOH group or an —OH group with a group capableof being desorbed by an acid.

An especially preferred acid-decomposable group in the invention is anacetal group or a tertiary ester group.

The parent resin in the case where the acid-decomposable group is bondedas the side chain is an alkali-soluble resin having an —OH group or a—COOH group on the side chain. For example, the later-describedalkali-soluble resins can be exemplified.

The alkali dissolution rate of these alkali-soluble resins is preferably170 Å/sec or more when measured using 0.261N tetramethylammoniumhydroxide (TMAH) at 23° C., especially preferably 330 Å/sec or more.

From this point of view, particularly preferred alkali-soluble resinsare o-, m-, p-poly(hydroxystyrene) and copolymers thereof, hydrogenatedpoly(hydroxystyrene), halogen- or alkyl-substitutedpoly(hydroxystyrene), a partially O-alkylated or O-acylated product ofpoly-(hydroxystyrene), styrene-hydroxystyrene copolymers,α-methylstyrene-hydroxystyrene copolymers, alkali-soluble resins havinga hydroxystyrene structure unit such as hydrogenated novolak resins,(meth)acrylic acid, and alkali-soluble resins containing a repeatingunit having a carboxyl group such as norbornenecarboxylic acid.

As repeating units having a preferred acid-decomposable group, e.g.,t-butoxycarbonyloxystyrene, 1-alkoxyethoxy-styrene, and (meth)acrylicacid tertiary alkyl ester are exemplified, and2-alkyl-2-adamantyl(meth)acrylate anddialkyl(1-adamantyl)methyl(meth)acrylate are more preferred.

Components (C) for use in the invention can be obtained, as disclosed inEP 254853, JP-A-2-25850, JP-A-3-223860 and JP-A-4-251259, by reacting analkali-soluble resin with the precursor of an acid-decomposable group,or copolymerizing an alkali-soluble resin monomer to which anacid-decomposable group is bonded with various monomers.

When the positive photosensitive composition of the invention isirradiated with KrF excimer laser beams, electron beams, X-rays, or highenergy rays of wavelength of 50 nm or lower (e.g., EUV), it is preferredfor a resin of component (C) to have a hydroxystyrene repeating unit,more preferably a copolymer of hydroxystyrene/hydroxystyrene protectedwith an acid-decomposable group, or hydroxystyrene/(meth)acrylic acidtertiary alkyl ester.

The specific examples of component (C) for use in the invention areshown below, but the invention is not restricted thereto.

In the above specific examples, tBu means a t-butyl group.

The content of an acid-decomposable group is expressed by B/(B+S),taking the number of the acid-decomposable groups in a resin as (B), andthe number of alkali-soluble groups not protected with acid-eliminablegroups as (S). The content is preferably from 0.01 to 0.7, morepreferably from 0.05 to 0.50, and still more preferably from 0.05 to0.40.

When the positive photosensitive composition in the invention isirradiated with ArF excimer laser beams, it is preferred that the resinof component (C) is a resin having a monocyclic or polycyclic alicyclichydrocarbon structure and capable of decomposing by the action of anacid to thereby increase the solubility in an alkali developingsolution.

As a resin having a monocyclic or polycyclic alicyclic hydrocarbonstructure and capable of decomposing by the action of an acid to therebyincrease the solubility in an alkali developing solution (hereinafteralso referred to as “an alicyclic hydrocarbon acid-decomposable resin”),a resin containing at least one repeating unit selected from the groupconsisting of a repeating unit having a partial structure containingalicyclic hydrocarbon represented by any of the following formulae (pI)to (pV), and a repeating unit represented by the following formula(II-AB) is preferred.

In formulae (pI) to (pV), R₁₁ represents a methyl group, an ethyl group,an n-propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, or a sec-butyl group; and Z represents an atomic group necessaryto form a cycloalkyl group together with a carbon atom.

R₁₂, R₁₃, R₁₄, R₁₅ and R₁₆ each represents a straight chain or branchedalkyl group, or a cycloalkyl group, provided that at least one of R₁₂ toR₁₄, or either R₁₅ or R₁₆ represents a cycloalkyl group.

R₁₇, R₁₈, R₁₉, R₂₀ and R₂, each represents a hydrogen atom, a straightchain or branched alkyl group or a cycloalkyl group, provided that atleast one of R₁₇ to R₂, represents a cycloalkyl group, and either R₁₉ orR₂, represents a straight chain or branched alkyl group or a cycloalkylgroup.

R₂₂, R₂₃, R₂₄ and R₂₅ each represents a hydrogen atom, a straight chainor branched alkyl group or a cycloalkyl group, provided that at leastone of R₂₂ to R₂₅ represents a cycloalkyl group, and R₂₃ and R₂₄ may bebonded to each other to form a ring.

In formula (II-AB), R₁₁′ and R₁₂′ each represents a hydrogen atom, acyano group, a halogen atom, or an alkyl group.

Z′ contains bonded two carbon atoms (C—C) and represents an atomic groupto form an alicyclic structure.

Formula (II-AB) is more preferably represented by the following formula(II-AB1) or (II-AB2).

In formulae (II-AB1) and (II-AB2), R₁₃′, R₁₄′, R₁₅′ and R₁₆′ eachrepresents a hydrogen atom, a halogen atom, a cyano group, —COOH,—COOR₅, a group decomposable by the action of an acid, —C(═O)—X-A′-R₁₇′,an alkyl group, or a cycloalkyl group. At least two of R₁₃′ to R₁₆′ maybe bonded to form a ring.

R₅ represents an alkyl group, a cycloalkyl group, or a group having alactone structure.

X represents an oxygen atom, a sulfur atom, —NH—, —NHSO₂ or —NHSO₂NH—.

A′ represents a single bond or a divalent linking group.

R₁₇′ represents —COOH, —COOR₅, —CN, a hydroxyl group, an alkoxyl group,—CO—NH—R₆, —CO—NH—SO₂—R₆, or a group having a lactone structure.

R₆ represents an alkyl group or a cycloalkyl group.

n represents 0 or 1.

The alkyl group represented by R₁₂ to R₂₅ in formulae (pI) to (pV) ispreferably a straight chain or branched alkyl group having from 1 to 4carbon atoms, e.g., a methyl group, an ethyl group, an n-propyl group,an isopropyl group, an n-butyl group, an isobutyl group, and a sec-butylgroup are exemplified.

The cycloalkyl groups represented by R₁₁ to R₂₅ or the cycloalkyl groupformed by Z and carbon atoms may be monocyclic or polycyclic.Specifically, groups having a monocyclic, bicyclic, tricyclic ortetracyclic structure having 5 or more carbon atoms can be exemplified.The number of carbon atoms of the groups is preferably from 6 to 30, andparticularly preferably from 7 to 25.

As preferred cycloalkyl groups, an adamantyl group, a noradamantylgroup, a decalin residue, a tricyclodecanyl group, a tetracyclododecanylgroup, a norbornyl group, a cedrol group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, acyclodecanyl group, and a cyclododecanyl group can be exemplified. Morepreferred cycloalkyl groups are an adamantyl group, a norbornyl group, acyclohexyl group, a cyclopentyl group, a tetracyclododecanyl group, anda tricyclodecanyl group.

These alkyl groups and cycloalkyl groups may have further substituents.As further substituents of these alkyl groups and cycloalkyl groups, analkyl group (having from 1 to 4 carbon atoms), a halogen atom, ahydroxyl group, an alkoxyl group (having from 1 to 4 carbon atoms), acarboxyl group, and an alkoxycarbonyl group (having from 2 to 6 carbonatoms) can be exemplified. As substituents that these alkyl group,alkoxyl group and alkoxycarbonyl group may further have, a hydroxylgroup, a halogen atom and an alkoxyl group can be exemplified.

The structures represented by formulae (pI) to (pV) in the resin can beused for the protection of alkali-soluble groups. As the alkali-solublegroups, various groups well known in this technical field can beexemplified.

Specifically, the structures in which the hydrogen atoms of carboxylicacid group, a sulfonic acid group, a phenol group and a thiol group aresubstituted with the structures represented by formulae (pI) to (pV) areexemplified, and preferably the structures in which the hydrogen atomsof carboxylic acid group and a sulfonic acid group are substituted withthe structures represented by formulae (pI) to (pV) are exemplified.

As the repeating unit having the alkali-soluble group protected with thestructure represented by any of the above formulae (pI) to (pV), arepeating unit represented by the following formula (pA) is preferred.

In formula (pA), R represents a hydrogen atom, a halogen atom, or astraight chain or branched alkyl group having from 1 to 4 carbon atoms,and a plurality of R's may be the same or different.

A represents a single group or the combination of two or more groupsselected from the group consisting of a single bond, an alkylene group,an ether group, a thioether group, a carbonyl group, an ester group, anamido group, a sulfonamido group, a urethane group, and a urea group. Asingle bond is preferred.

R_(p1) represents a group represented by any of formulae (pI) to (pVI).

The repeating unit represented by (pA) is most preferably a repeatingunit by 2-alkyl-2-adamantyl(meth)acrylate anddialkyl(1-adamantyl)methyl(meth)acrylate.

The specific examples of the repeating units represented by formula (pA)are shown below, but the invention is not restricted thereto.

(In the formulae, Rx represents H, CH₃, CF₃, CH₂OH, Rxa, and Rxb eachrepresents an alkyl group having from 1 to 4 carbon atoms.)

As the halogen atoms represented by R₁₁′ and R₁₂′ in formula (II-AB), achlorine atom, a bromine atom, a fluorine atom and an iodine atom areexemplified.

As the alkyl groups represented by R₁₁′ and R₁₂′, straight chain orbranched alkyl groups having from 1 to 10 carbon atoms are exemplified.

The atomic group represented by Z′ to form an alicyclic structure is anatomic group to form a repeating unit having an alicyclic hydrocarbonstructure, which may have a substituent, and an atomic group to form arepeating unit having a bridged alicyclic hydrocarbon structure ispreferred above all.

As the skeleton of alicyclic hydrocarbon formed, the same alicyclichydrocarbon groups as represented by R₁₂ to R₂₅ in formulae (pI) to (pV)are exemplified.

The skeleton of the alicyclic hydrocarbon structure may have asubstituent, and as the substituents, the groups represented by R₁₃′ toR₁₆′ in formula (II-AB1) or (II-AB2) can be exemplified.

In the alicyclic hydrocarbon-based acid-decomposable resin in theinvention, a group capable of decomposing by the action of an acid canbe contained in at least one repeating unit of a repeating unit having apartial structure containing alicyclic hydrocarbon represented by any offormulae (pI) to (pV), a repeating unit represented by formula (II-AB),and a repeating unit of the later-described copolymer component.

Various substituents of R₁₃′ to R₁₆′ in formula (II-AB1) or (II-AB2) canalso be used as the substituents of the atomic group to form analicyclic hydrocarbon structure in formula (II-AB), or atomic group Z toform a bridged alicyclic hydrocarbon structure.

The specific examples of the repeating units represented by formula(II-AB1) or (II-AB2) are shown below, but the invention is notrestricted thereto.

The alicyclic hydrocarbon-based acid-decomposable resin in the inventionpreferably contains a repeating unit having a group having a lactonestructure. As the group having a lactone structure, any group having alactone structure can be used, but preferably groups having 5- to7-membered ring lactone structures, and 5- to 7-membered ring lactonestructures condensed with other ring structures in the form of forming abicyclo structure or a spiro structure are preferred. As the grouphaving a lactone structure, a group having a lactone structurerepresented by any of the following formulae (LC1-1) to (LC1-16) is morepreferred. A group having a lactone structure may be directly bonded tothe main chain of a repeating unit. Preferred lactone structures are(LC1-1), (LC1-4) (LC1-5), (LC1-6), (LC1-13) and (LC1-14). By the use ofa specific lactone structure, line edge roughness and development defectare bettered.

A lactone structure moiety may have or may not have a substituent (Rb₂).As preferred substituent (Rb₂), an alkyl group having from 1 to 8 carbonatoms, a cycloalkyl group having from 3 to 7 carbon atoms, an alkoxylgroup having from 1 to 8 carbon atoms, an alkoxycarbonyl group havingfrom 1 to 8 carbon atoms, a carboxyl group, a halogen atom, a hydroxylgroup, a cyano group, and an acid-decomposable group are exemplified. n₂represents an integer of from 0 to 4. When n₂ is 2 or more, a pluralityof Rb₂ may be the same or different, and a plurality of Rb₂ may bebonded to each other to form a ring.

As the repeating units having a group having a lactone structurerepresented by any of formulae (LC1-1) to (LC1-16), a repeating unit inwhich at least one of R₁₃′ to R₁₆′ in formula (II-AB1) or (II-AB2) is agroup having a lactone structure represented by any of formulae (LC1-1)to (LC1-16) (for example, R₅ of —COOR₅ is a group having a lactonestructure represented by any of formulae (LC1-1) to (LC1-16)), or arepeating unit represented by the following formula (AI) can beexemplified.

In formula (AI), Rb₀ represents a hydrogen atom, a halogen atom, or analkyl group having from 1 to 4 carbon atoms. As the preferredsubstituents that the alkyl group represented by Rb₀ may have, ahydroxyl group and a halogen atom are exemplified.

As the halogen atom represented by Rb₀, a fluorine atom, a chlorineatom, a bromine atom and an iodine atom can be exemplified.

Rb₀ preferably represents a hydrogen atom or a methyl group.

Ab represents a single bond, an alkylene group, a divalent linking grouphaving a monocyclic or polycyclic alicyclic hydrocarbon structure, anether group, an ester group, a carbonyl group, a carboxyl group, or adivalent linking group combining these groups.

Ab preferably represents a single bond or a linking group represented by-Ab₁-CO₂—. Ab₁ represents a straight chain or branched alkylene group,or a monocyclic or polycyclic cycloalkylene group, and preferably amethylene group, an ethylene group, a cyclohexyl group, an adamantylgroup, or a norbornyl group.

V represents a group having a lactone structure represented by any offormulae (LC1-1) to (LC1-16).

Repeating units having a lactone structure generally have opticalisomers, and any optical isomer may be used. One kind of optical isomermay be used alone, or a plurality of optical isomers may be used asmixture. When one kind of optical isomer is mainly used, the opticalpurity (ee) of the optical isomer is preferably 90 or more, and morepreferably 95 or more.

The specific examples of repeating units having a group having a lactonestructure are shown below, but the invention is not limited thereto.

(In the formulae, Rx represents H, CH₃, CH₂OH or CF₃.)

(In the formulae, Rx represents H, CH₃, CH₂OH or CF₃.)

(In the formulae, Rx represents H, CH₃, CH₂OH or CF₃.)

It is preferred for the alicyclic hydrocarbon-based acid-decomposableresin of the invention to have a repeating unit having a group having analicyclic hydrocarbon structure substituted with a polar group, by whichadhesion with a substrate and affinity with a developing solution areimproved. As the alicyclic hydrocarbon structure of the alicyclichydrocarbon structure substituted with a polar group, an adamantylgroup, a diamantyl group, and a norbornane group are preferred. As thepolar group, a hydroxyl group and a cyano group are preferred. As thegroup having the alicyclic hydrocarbon structure substituted with apolar group, a group represented by any of the following formulae (VIIa)to (VIId) is preferred.

In formula (VIIa) to (VIIc), R_(2c), R_(3c), and R_(4c) each representsa hydrogen atom, a hydroxyl group, or a cyano group, provided that atleast one of R_(2c), R₃, and R_(4c) represents a hydroxyl group or acyano group. Preferably one or two of R_(2c), R_(3c) and R_(4c)represent a hydroxyl group and the remainder represent a hydrogen atom.In formula (VIIa), more preferably two of R_(2c), R_(3c) and R_(4c)represent a hydroxyl group and the remainder represents a hydrogen atom.

As the repeating unit having a group represented by any of formulae(VIIa) to (VIId), a repeating unit in which at least one of R₁₃′ to R₁₆′in formula (II-AB1) or (II-AB2) is a group represented by any offormulae (VIIa) to (VId) (for example, R₅ of —COOR₅ is a grouprepresented by any of formulae (VIIa) to (VIId)), or a repeating unitrepresented by any of the following formulae (AIIa) to (AIId) can beexemplified.

In formulae (AIIa) to (AIId), R_(1c) represents a hydrogen atom, amethyl group, a trifluoromethyl group, or a hydroxymethyl group.

The specific examples of the repeating units represented by formulae(AIIa) to (AIId) are shown below, but the invention is not restrictedthereto.

The alicyclic hydrocarbon-based acid-decomposable resin in the inventionmay have a repeating unit represented by the following formula (VIII).

In formula (VIII), Z₂ represents —O— or —N(R₄₁)—. R₄₁ represents ahydrogen atom, a hydroxyl group, an alkyl group, or —OSO₂—R₄₂. R₄₂represents an alkyl group, a cycloalkyl group, or a camphor residue. Thealkyl group represented by R₄₁, and R₄₂ may be substituted with ahalogen atom (preferably a fluorine atom) and the like.

As the specific examples of the repeating units represented by formula(VIII), the following compounds are exemplified, but the invention isnot restricted thereto.

It is preferred for the alicyclic hydrocarbon-based acid-decomposableresin in the invention to have a repeating unit having an alkali-solublegroup, and it is more preferred to have a repeating unit having acarboxyl group, by which the resolution in the use for contact hole isenhanced. As the repeating units having a carboxyl group, a repeatingunit having a carboxyl group directly bonded to the main chain of aresin such as a repeating unit by acrylic acid or methacrylic acid, arepeating unit having a carboxyl group bonded to the main chain of aresin via a linking group, and a repeating unit having a carboxyl groupintroduced to the terminals of a polymer chain by polymerization with apolymerization initiator having an alkali-soluble group and a chaintransfer agent are exemplified, and any of these repeating units ispreferably used. Linking groups may have a monocyclic or polycyclichydrocarbon structure. The repeating unit by acrylic acid or methacrylicacid is especially preferred.

The alicyclic hydrocarbon-based acid-decomposable resin in the inventionmay further have a repeating unit having one to three groups representedby the following formula (F1), by which line edge roughness property isimproved.

In formula (F1), R₅₀, R₅₁, R₅₂, R₅₃, R₅₄ and R₅₅ each represents ahydrogen atom, a fluorine atom, or an alkyl group, provided that atleast one of R₅₀ to R₅₅ represents a fluorine atom, or an alkyl group inwhich at least one hydrogen atom is substituted with a fluorine atom.

Rxa represents a hydrogen atom or an organic group (preferably anacid-decomposable protective group, an alkyl group, a cycloalkyl group,an acyl group, or an alkoxycarbonyl group).

The alkyl group represented by R₅₀ to R₅₅ may be substituted with ahalogen atom, e.g., a fluorine atom, or a cyano group, and preferably analkyl group having from 1 to 3 carbon atoms, e.g., a methyl group and atrifluoromethyl group can be exemplified.

It is preferred that all of R₅₀ to R₅₅ represent a fluorine atom.

As the organic group represented by Rxa, an acid-decomposable protectivegroup, and an alkyl group, a cycloalkyl group, an acyl group, analkylcarbonyl group, an alkoxycarbonyl group, an alkoxycarbonylmethylgroup, an alkoxymethyl group, and a 1-alkoxyethyl group, each of whichmay have a substituent, are preferred.

The repeating unit having the group represented by formula (F1) ispreferably a repeating unit represented by the following formula (F2).

In formula (F2), Rx represents a hydrogen atom, a halogen atom, or analkyl group having from 1 to 4 carbon atoms. As preferred substituentsthat the alkyl group represented by Rx may have, a hydroxyl group and ahalogen atom are exemplified.

Fa represents a single bond or a straight chain or branched alkylenegroup, and preferably a single bond.

Fb represents a monocyclic or polycyclic hydrocarbon group.

Fc represents a single bond or a straight chain or branched alkylenegroup, and preferably a single bond or a methylene group.

F₁ represents a group represented by formula (F1).

P₁ is from 1 to 3.

As the cyclic hydrocarbon group represented by Fb, a cyclopentyl group,a cyclohexyl group, or a norbornyl group is preferred.

The specific examples of the repeating units having the grouprepresented by formula (F1) are shown below, but the invention is notrestricted thereto.

The alicyclic hydrocarbon-based acid-decomposable resin in the inventionmay further contain a repeating unit having an alicyclic hydrocarbonstructure and not showing acid decomposability, by containing such arepeating unit, the elution of low molecular weight components from aresist film into an immersion liquid can be reduced at the time ofimmersion exposure. As such repeating units, e.g.,1-adamantyl(meth)acrylate, tricyclodecanyl(meth)acrylate, andcyclohexyl(meth)acrylate, are exemplified.

The alicyclic hydrocarbon-based acid-decomposable resin in the inventioncan contain various kinds of repeating structural units, besides theabove repeating structural units, for the purpose of the adjustments ofdry etching resistance, aptitude for standard developing solutions,adhesion to a substrate, resist profile, and further, general requisitecharacteristics of resists, e.g., resolution, heat resistance andsensitivity.

As these repeating structural units, the repeating structural unitscorresponding to the monomers shown below can be exemplified, but theinvention is not restricted thereto.

By containing such various repeating structural units, fine adjustmentof performances required of the alicyclic hydrocarbon-basedacid-decomposable resin, in particular the following performances,becomes possible, that is,

-   (1) Solubility in a coating solvent,-   (2) A film-forming property (a glass transition point),-   (3) Alkali developability,-   (4) Decrease of layer thickness (hydrophobic-hydrophilic property,    selection of an alkali-soluble group),-   (5) Adhesion of an unexposed area to a substrate, and-   (6) Dry etching resistance.

The examples of such monomers include compounds having one additionpolymerizable unsaturated bond selected from acrylic esters, methacrylicesters, acrylamides, methacryl-amides, allyl compounds, vinyl ethers,vinyl esters, etc.

In addition to the aforementioned compounds, addition polymerizableunsaturated compounds copolymerizable with the monomers corresponding tothe above various repeating structural units may be used forcopolymerization.

In the alicyclic hydrocarbon-based acid-decomposable resin, the molarratio of the content of each repeating structural unit is arbitrarilyset to adjust dry etching resistance and aptitude for standarddeveloping solutions of a resist, adhesion to a substrate, and resistprofile, in addition, general requisite characteristics of a resist,e.g., resolution, heat resistance and sensitivity.

As preferred embodiments of the alicyclic hydrocarbon-basedacid-decomposable resin in the invention, the following resins areexemplified.

-   (1) A resin containing a repeating unit having a partial structure    containing the alicyclic hydrocarbon represented by any of formulae    (pI) to (pV) (a side chain type), preferably a resin containing a    (meth)acrylate repeating unit having the structure of any of    formulae (pI) to (pV);-   (2) A resin containing a repeating unit represented by formula    (II-AB) (a main chain type); however, the following is further    exemplified as embodiment (2):-   (3) A resin containing a repeating unit represented by formula    (II-AB), a maleic anhydride derivative and a (meth)acrylate    structure (a hybrid type).

In the alicyclic hydrocarbon-based acid-decomposable resin, the contentof a repeating unit having an acid-decomposable group is preferably from10 to 60 mol % in the total repeating structural units, more preferablyfrom 20 to 50 mol %, and still more preferably from 25 to 40 mol %.

In the alicyclic hydrocarbon-based acid-decomposable resin, the contentof a repeating unit having a partial structure containing the alicyclichydrocarbon represented by any of formulae (pI) to (pV) is preferablyfrom 20 to 70 mol % in the total repeating structural units, morepreferably from 20 to 50 mol %, and still more preferably from 25 to 40mol %.

In the alicyclic hydrocarbon-based acid-decomposable resin, the contentof a repeating unit represented by formula (II-AB) is preferably from 10to 60 mol % in the total repeating structural units, more preferablyfrom 15 to 55 mol %, and still more preferably from 20 to 50 mol %.

The content of the repeating structural units on the basis of themonomers of further copolymerization components in the resin can also beoptionally set according to the desired resist performances, and thecontent is generally preferably 99 mol % or less to the total mol numberof the repeating structural units having a partial structure containingthe alicyclic hydrocarbon represented by any of formulae (pI) to (pV)and the repeating units represented by formula (II-AB), more preferably90 mol % or less, and still more preferably 80 mol % or less.

When the composition in the invention is for ArF exposure, it ispreferred that the resin does not have an aromatic group from the aspectof the transparency to ArF rays.

The alicyclic hydrocarbon-based acid-decomposable resin for use in theinvention is preferably such that all the repeating units consist of(meth)acrylate repeating units. In this case, any of the following casescan be used, that is, a case where all the repeating units consist ofmethacrylate, a case where all the repeating units consist of acrylate,and a case where the repeating units consist of mixture of methacrylateand acrylate, but it is preferred that acrylate repeating units accountfor 50 mol % or less of all the repeating units. More preferred resinsare ternary copolymers comprising from 20 to 50 mol % of repeating unitshaving a partial structure containing the alicyclic hydrocarbonrepresented by any of formulae (pI) to (pV), from 20 to 50 mol % ofrepeating units having a lactone structure, and from 5 to 30 mol % ofrepeating units having an alicyclic hydrocarbon structure substitutedwith a polar group, and quaternary copolymers further containing from 0to 20 mol % of other repeating units.

Especially preferred resins are ternary copolymers comprising from 20 to50 mol % of a repeating unit having an acid-decomposable grouprepresented by any of the following formulae (ARA-1) to (ARA-5), from 20to 50 mol % of a repeating unit having a lactone group represented byany of the following formulae (ARL-1) to (ARL-6), and from 5 to 30 mol %of a repeating unit having an alicyclic hydrocarbon structuresubstituted with a polar group represented by any of the followingformulae (ARH-1) to (ARH-3), and quaternary copolymers furthercontaining from 5 to 20 mol % of a repeating unit having a carboxylgroup or a structure represented by formula (F1), and a repeating unithaving an alicyclic hydrocarbon structure and not showing aciddecomposability.

In the above formulae, Rxy₁ represents a hydrogen atom or a methylgroup.

Rxa₁ and Rxb₁ each represents a methyl group or an ethyl group.

The alicyclic hydrocarbon-based acid-decomposable resins for use in theinvention can be synthesized according to ordinary methods (e.g.,radical polymerization). For instance, as ordinary methods, a batchpolymerization method of dissolving a monomer and an initiator in asolvent and heating the solution to perform polymerization, and adropping polymerization method of adding a solution of a monomer and aninitiator to a heated solvent over 1 to 10 hours by dropping areexemplified, and dropping polymerization is preferred. As reactionsolvents, ethers, e.g., tetrahydrofuran, 1,4-dioxane, and diisopropylether, ketones, e.g., methyl ethyl ketone and methyl isobutyl ketone, anester solvent, e.g., ethyl acetate, amide solvents, e.g.,dimethylformamide and dimethyacetamide, and the later-described solventscapable of dissolving the composition of the invention, e.g., propyleneglycol monomethyl ether acetate, propylene glycol monomethyl ether, andcyclohexanone are exemplified. It is more preferred to use the samesolvent in polymerization as the solvent used in the resist compositionin the invention, by which the generation of particles duringpreservation can be restrained.

It is preferred to perform polymerization reaction in the atmosphere ofinert gas such as nitrogen or argon. Polymerization is initiated withcommercially available radical polymerization initiators (e.g., azoinitiators, peroxide and the like). As radical polymerizationinitiators, azo initiators are preferred, and azo initiators having anester group, a cyano group, or a carboxyl group are preferred. Aspreferred initiators, azobisisobutyronitrile,azobis-dimethylvaleronitrile, dimethyl-2,2′-azibis(2-methyl-propionate),etc., are exemplified. Initiators are added additionally or dividedly,if desired, and after termination of the reaction, the reaction productis put into a solvent and an objective polymer is recovered as powder ora solid state. The reaction concentration is from 5 to 50 mass %, andpreferably from 10 to 30 mass %. The reaction temperature is generallyfrom 10 to 150° C., preferably from 30 to 120° C., and more preferablyfrom 60 to 100° C.

When the photosensitive composition according to the invention is usedin the upper layer resist of a multilayer resist, it is preferred thatthe resin of component (C) should have a silicon atom.

As resins having a silicon atom and capable of decomposing by the actionof an acid to thereby increase the solubility in an alkali developingsolution, resins having a silicon atom at least on one side of the mainchain and the side chain can be used. As resins having a siloxanestructure on the side chain of resins, copolymer of, e.g., an olefinmonomer having a silicon atom on the side chain, and a (meth)acrylicacid monomer having maleic anhydride and an acid decomposable group onthe side chain.

As resins having a silicon atom, resins having a trialkylsilyl structureand a monocyclic or polycyclic siloxane structure are preferred, resinshaving repeating units having the structures represented by any of thefollowing formulae (SS-1) to (SS-4) are more preferred, and(meth)acrylic ester repeating units having the structures represented byany of formulae (SS-1) to (SS-4), vinyl repeating units, and allylrepeating units are still more preferred.

In formulae (SS-1) to (SS-4), Rs represents an alkyl group having from 1to 5 carbon atoms, preferably a methyl group or an ethyl group.

It is preferred that resins having silicon atoms have two or more kindsof different repeating units having silicon atoms, resins having both(Sa) repeating unit having from 1 to 4 silicon atoms and (Sb) repeatingunit having from 5 to 10 silicon atoms are more preferred, and resinshaving at least one repeating unit having a structure represented by anyof formulae (SS-1) to (SS-3) and a repeating unit having a structurerepresented by formula (SS-4) are still more preferred.

When the positive photosensitive composition of the invention isirradiated with F₂ excimer laser beams, the resin of component (C) ispreferably a resin having a structure wherein the main chain and/or sidechain of the polymer skeleton are substituted with fluorine atoms andcapable of decomposing by the action of an acid to increase thesolubility in an alkali developing solution (hereinafter also referredto as “a fluorine-based acid-decomposable resin), the resin is morepreferably a resin having a hydroxyl group the 1-position of which issubstituted with a fluorine atom or a fluoroalkyl group, or having agroup obtained by protecting a hydroxyl group the 1-position of which issubstituted with a fluorine atom or a fluoroalkyl group with anacid-decomposable group. The especially preferred resin is a resinhaving a hexafluoro-2-propanol structure, or a resin having a structurethat the hydroxyl group of hexafluoro-2-propanol is protected with anacid-decomposable group. By the incorporation of fluorine atoms, thetransparency to the far ultraviolet rays, in particular to F₂ ray (157nm) can be improved.

As the fluorine-based acid-decomposable resin, resins having at leastone repeating unit represented by any of the following formulae (FA) to(FG) are preferably exemplified.

In the above formulae, R₁₀₀, R₁₀₁, R₁₀₂ and R₁₀₃ each represents ahydrogen atom, a fluorine atom, an alkyl group, or an aryl group.

R₁₀₄ and R₁₀₆ each represents a hydrogen atom, a fluorine atom, or analkyl group, and at least one of R₁₀₄ and R₁₀₆ represents a fluorineatom or a fluoroalkyl group. Preferably both R₁₀₄ and R₁₀₆ represent atrifluoromethyl group.

R₁₀₅ represents a hydrogen atom, an alkyl group, a cycloalkyl group, anacyl group, an alkoxycarbonyl group, or a group decomposable by theaction of an acid.

A₁ represents a single bond, a divalent linking group, e.g., an alkylenegroup, a cycloalkylene group, an alkenylene group, an arylene group,—OCO—, —COO—, —CON(R₂₄)—, or a linking group containing a plurality ofthese groups. R₂₄ represents a hydrogen atom or an alkyl group.

R₁₀₇ and R₁₀₈ each represents a hydrogen atom, a halogen atom, an alkylgroup, an alkoxyl group, an alkoxycarbonyl group, or a groupdecomposable by the action of an acid.

R₁₀₉ represents a hydrogen atom, an alkyl group, a cycloalkyl group, ora group decomposable by the action of an acid.

b represents 0, 1 or 2.

Further, R₁₀₀ and R₁₀₁ in formulae (FA) and (FC) may form a ring throughan alkylene group (having from 1 to 5 carbon atoms) which may besubstituted with a fluorine atom.

The repeating units represented by formulae (FA) to (FG) have at least1, preferably 3 or more, fluorine atoms per one repeating unit.

In formulae (FA) to (FG), the alkyl group is an alkyl group having from1 to 8 carbon atoms, specifically, a methyl group, an ethyl group, apropyl group, an n-butyl group, a sec-butyl group, a hexyl group, a2-ethylhexyl group, and an octyl group are preferably exemplified.

The cycloalkyl group may be monocyclic or polycyclic. As the monocycliccycloalkyl groups, those having from 3 to 8 carbon atoms, e.g., acyclopropyl group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, and a cyclooctyl group are preferably exemplified. Asthe polycyclic groups, preferably those having from 6 to 20 carbonatoms, e.g., an adamantyl group, a norbornyl group, an isoboronyl group,a camphanyl group, a dicyclopentyl group, an α-pinel group, atricyclodecanyl group, a tetracyclododecyl group, and an androstanylgroup are exemplified. However, the carbon atoms in the monocyclic orpolycyclic cycloalkyl groups may be substituted with hetero atoms suchas an oxygen atom, etc.

The fluoroalkyl group is a fluoroalkyl group having from 1 to 12 carbonatoms, and specifically a trifluoromethyl group, a perfluoroethyl group,a perfluoropropyl group, a perfluoro-butyl group, a perfluorohexylgroup, a perfluorooctyl group, a perfluorooctylethyl group, and aperfluorododecyl group are preferably exemplified.

The aryl group is an aryl group having from 6 to 15 carbon atoms, andspecifically a phenyl group, a tolyl group, a dimethylphenyl group, a2,4,6-trimethylphenyl group, a naphthyl group, an anthryl group and a9,10-dimethoxyanthryl group are preferably exemplified.

The alkoxyl group is an alkoxyl group having from 1 to 8 carbon atoms,and specifically a methoxy group, an ethoxy group, an n-propoxy group,an isopropoxy group, a butoxy group, a pentoxy group, an allyloxy group,and an octoxy group are preferably exemplified.

The acyl group is an acyl group having from 1 to 10 carbon atoms, andspecifically a formyl group, an acetyl group, a propanoyl group, abutanoyl group, a pivaloyl group, an octanoyl group, and a benzoyl groupare preferably exemplified.

As the alkoxycarbonyl group, an i-propoxycarbonyl group, at-butoxycarbonyl group, a t-amyloxycarbonyl group, and a1-methyl-1-cyclohexyloxycarbonyl group, preferably a secondary, and morepreferably a tertiary alkoxycarbonyl group are exemplified.

As the halogen atom, e.g., a fluorine atom, a chlorine atom, a bromineatom and an iodine atom are exemplified.

As the alkylene group, preferably an alkylene group having from 1 to 8carbon atoms, e.g., a methylene group, an ethylene group, a propylenegroup, a butylene group, a hexylene group, and an octylene group areexemplified.

As the alkenylene group, preferably an alkenylene group having from 2 to6 carbon atoms, e.g., an ethenylene group, a propenylene group and abutenylene group are exemplified.

As the cycloalkylene group, preferably a cycloalkylene group having from5 to 8 carbon atoms, e.g., a cyclopentylene group and a cyclohexylenegroup are exemplified.

As the arylene group, preferably an arylene group having from 6 to 15carbon atoms, e.g., a phenylene group, a tolylene group and anaphthylene group are exemplified.

These groups may have a substituent, and the examples of thesubstituents include groups having active hydrogen, e.g., an alkylgroup, a cycloalkyl group, an aryl group, an amino group, an amidogroup, a ureido group, a urethane group, a hydroxyl group, and acarboxyl group, a halogen atom (e.g., a fluorine atom, a chlorine atom,a bromine atom, and an iodine atom), an alkoxyl group (e.g., a methoxygroup, an ethoxy group, a propoxy group, a butoxy group), a thioethergroup, an acyl group (e.g., an acetyl group, a propanoyl group, abenzoyl group), an acyloxy group (e.g., an acetoxy group, a propanoyloxygroup, a benzoyloxy group), an alkoxycarbonyl group (e.g., amethoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonylgroup), a cyano group, and a nitro group are exemplified.

Here, as the alkyl, cycloalkyl and aryl groups, those described aboveare exemplified, but the alkyl group may further be substituted with afluorine atom or a cycloalkyl group.

As the groups capable of decomposing by the action of an acid toincrease the solubility in an alkali developing solution contained inthe fluorine-based acid-decomposable resins, e.g., —O—C(R₃₆)(R₃₇)(R₃₈),—O—C(R₃₆)(R₃₇)(OR₃₉), —O—COO—C(R₃₆)(R₃₇)(R₃₈),—O—C(R₀₁)(R₀₂)COO—C(R₃₆)(R₃₇)(R₃₈), —COO—C(R₃₆)(R₃₇)(R₃₈), and—COO—C(R₃₆)(R₃₇)(OR₃₉) can be exemplified.

R₃₆, R₃₇, R₃₈ and R₃₉ each represents an alkyl group, a cycloalkylgroup, an aryl group, an aralkyl group, or an alkenyl group; R₀₁ and R₀₂each represents a hydrogen atom, an alkyl group, a cycloalkyl group, analkenyl group (e.g., a vinyl group, an allyl group, a butenyl group, acyclohexenyl group), an aralkyl group (e.g., a benzyl group, a phenethylgroup, a naphthylmethyl group), or an aryl group.

The preferred specific examples of the groups include the ether groupsor the ester groups of tertiary alkyl groups such as a t-butyl group, at-amyl group, a 1-alkyl-1-cyclohexyl group, a 2-alkyl-2-adamantyl group,a 2-adamantyl-2-propyl group, and a 2-(4-methylcyclohexyl)-2-propylgroup, acetal groups or acetal ester groups such as a 1-alkoxy-1-ethoxygroup and a tetrahydropyranyl group, a t-alkylcarbonate group and at-alkylcarbonylmethoxy group.

The specific examples of the repeating units represented by formulae(FA) to (FG) are shown below, but the invention is not restrictedthereto.

The total content of the repeating units represented by formulae (FA) to(FG) is generally from 10 to 80 mol % to all the repeating unitsconstituting the resin, preferably from 30 to 70 mol %, and morepreferably from 35 to 65 mol %.

For the purpose of further improving the performances of the resist ofthe invention, the fluorine-based acid-decomposable resins may furtherbe copolymerized with other polymerizable monomers in addition to theabove repeating structural units.

As the usable copolymerizable monomers, compounds having one additionpolymerizable unsaturated bond selected from acrylic esters,acrylamides, methacrylic esters, methacryl-amides, allyl compounds,vinyl ethers, vinyl esters, styrens, and crotonic esters other thandescribed above are exemplified.

It is preferred that these fluorine-based acid-decomposable resinscontain other repeating units as the copolymerization components besidesthe above repeating units having fluorine atoms from the points ofimproving dry etching resistance, adjusting alkali solubility, andimproving adhesion with substrates. Preferred other repeating units areas follows.

-   1) The repeating units having an alicyclic hydrocarbon structure    represented by any of formulae (pI) to (pVI) and formula (II-AB).    Specifically the above exemplified repeating units 1 to 23 and    repeating units [II-1] to [II-32] shown above. Preferably repeating    units 1 to 23, wherein Rx represents CF₃.-   2) The repeating units having a lactone structure represented by    formula (Lc) and any of formulae (V-1) to (V-5). Specifically the    above-exemplified repeating units, in particular, the    above-exemplified repeating units represented by formula (Lc) and    formulae (V-1) to (V-4).-   3) The repeating units derived from the vinyl compounds having    maleic anhydride, vinyl ether or a cyano group represented by the    following formula (XV), (XVI) or (XVII). Specifically repeating    units (C-1) to (C-15) shown below. These repeating units may or may    not contain a fluorine atom.

In the above formulae, R₄₁ represents an alkyl group, a cycloalkylgroup, an aralkyl group, or an aryl group, and the alkyl grouprepresented by R₄₁ may be substituted with an aryl group.

R₄₂ represents a hydrogen atom, a halogen atom, a cyano group, or analkyl group.

A₅ represents a single bond, a divalent alkylene group, alkenylenegroup, cycloalkylene group, or arylene group, or —O—CO—R₂₂—, —CO—O—R₂₃—,or —CO—N(R₂₄)—R₂₅—.

R₂₂, R₂₃ and R₂₅, which may be the same or different, each represents asingle bond, or a divalent alkylene group, alkenylene group,cycloalkylene group or arylene group which may have an ether group, anester group, an amido group, a urethane group or a ureido group.

R₂₄ represents a hydrogen atom, an alkyl group, a cycloalkyl group, anaralkyl group, or an aryl group.

Here, as the examples of the substituents, the same groups as thesubstituents in formulae (FA) to (FG) can be exemplified.

The specific examples of the repeating structural units represented byformulae (XV) to (XVII) are shown below, but the invention is notrestricted thereto.

The total amount of the repeating units represented by any of formulae(XV) to (XVII) and other repeating units is generally from 0 to 70 mol %to the total repeating units constituting the resin, preferably from 10to 60 mol %, and more preferably from 20 to 50 mol %.

The fluorine-based acid-decomposable resins may contain anacid-decomposable group in any repeating unit.

The content of a repeating unit having an acid decomposable group ispreferably from 10 to 70 mol % to the total repeating units, morepreferably from 20 to 60 mol %, and still more preferably from 30 to 60mol %.

The fluorine-based acid-decomposable resins can be synthesized byradical polymerization almost similar to the synthesis of alicyclichydrocarbon-based acid-decomposable resins.

The weight average molecular weight of the resin of component (C) ispreferably from 2,000 to 200,000 as the polystyrene equivalent by theGPC method. By making the weight average molecular weight 2,000 or more,heat resistance and dry etching resistance can be improved, and bymaking the weight average molecular weight 200,000 or less,developability can be improved, and film-forming property can beheightened, since the viscosity becomes low. The weight averagemolecular weight is more preferably from 5,000 to 50,000, and still morepreferably from 7,000 to 30,000. By the adjustment of the molecularweight, it is possible to reconcile the heat resistance of thecomposition, resolution, development failure and the like. The degree ofdispersion of molecular weight (Mw/Mn) of the resin of component (C) ispreferably from 1.0 to 3.0, more preferably from 1.2 to 2.5, and stillmore preferably from 1.2 to 1.6. By the adjustment of the degree ofdispersion to a proper range, the performance of line edge roughness canbe increased.

In the positive photosensitive composition in the invention, theproportion of the resin of component (C) of the invention in the entirecomposition is preferably from 40 to 99.99 mass % in the total solidscontent, more preferably from 50 to 99 mass %, and still more preferablyfrom 80 to 96 mass %.

-   [4] (D) A dissolution inhibiting compound capable of decomposing by    the action of an acid to increase solubility in an alkali developing    solution having a molecular weight of 3,000 or less (hereinafter    also referred to as “component (D)” or “dissolution inhibiting    compound”):

As (D) the dissolution inhibiting compound capable of decomposing by theaction of an acid to thereby increase the solubility in an alkalideveloping solution having a molecular weight of 3,000 or less,alicyclic or aliphatic compounds containing an acid-decomposable group,such as cholic acid derivatives containing an acid-decomposable groupdescribed in Proceeding of SPIE, 2724, 355 (1996) are preferred so asnot to reduce the permeability to lights of 220 nm or less. Asacid-decomposable groups and alicyclic structures, the same as thosedescribed above in the alicyclic hydrocarbon-based acid-decomposableresin are exemplified.

When the photosensitive composition of the invention is exposed with aKrF excimer laser or irradiated with electron beams, a phenolic compoundhaving a structure that the phenolic hydroxyl group is substituted withan acid-decomposable group is preferably used. As the phenoliccompounds, compounds having from 1 to 9 phenolic skeletons arepreferred, and those having from 2 to 6 are more preferred.

The molecular weight of the dissolution-inhibiting compound in theinvention is 3,000 or less, preferably from 300 to 3,000, and morepreferably from 500 to 2,500.

The addition amount of the dissolution-inhibiting compound is preferablyfrom 3 to 50 mass % based on the solids content of the photosensitivecomposition, and more preferably from 5 to 40 mass %.

The specific examples of the dissolution-inhibiting compounds are shownbelow, but the invention is not restricted thereto.

-   [5] (E) A resin soluble in an alkali developing solution    (hereinafter also referred to as “component (E)” or “alkali-soluble    resin”):

The alkali dissolution rate of alkali-soluble resins is preferably 20Å/sec or more when measured with 0.261 N tetramethylammonium hydroxide(TMAH) at 23° C., and especially preferably 200 Å/sec or more.

As alkali-soluble resins for use in the invention, e.g., novolak resins,hydrogenated novolak resins, acetone-pyrogallol resins,o-polyhydroxystyrene, m-polyhydroxy-styrene, p-polyhydroxystyrene,hydrogenated polyhydroxy-styrene, halogen- or alkyl-substitutedpolyhydroxystyrene, hydroxystyrene-N-substituted maleimide copolymers,o/p- and m/p-hydroxystyrene copolymers, partially O-alkylated productsof the hydroxyl group of polyhydroxystyrene (e.g., from 5 to 30 mol %O-methylated, O-(1-methoxy)ethylated, O-(1-ethoxy)ethylated,O-2-tetrahydropyranylated, and O-(t-butoxycarbonyl)methylated products),or partially O-acylated products (e.g., from 5 to 30 mol % o-acetylatedand O-(t-butoxy)carbonylated products), styrene-maleic anhydridecopolymers, styrene-hydroxystyrene copolymers,α-methylstyrene-hydroxystyrene copolymers, carboxyl group-containingmethacrylic resins and derivatives thereof, and polyvinyl alcoholderivatives can be exemplified, but the invention is not limited tothese resins.

Particularly preferred alkali-soluble resins are novolak resins,o-polyhydroxystyrene, m-polyhydroxystyrene p-polyhydroxystyrene,copolymers of them, alkyl-substituted polyhydroxystyrene, partiallyO-alkylated or O-acylated products of polyhydroxystyrene,styrene-hydroxystyrene copolymers, and α-methylstyrene-hydroxystyrenecopolymers.

The novolak resins can be obtained by addition condensation to aldehydeswith the prescribed monomers as main components in the presence of acidcatalysts.

The weight average molecular weight of alkali-soluble resins is 2,000 ormore, preferably from 5,000 to 200,000, and more preferably from 5,000to 100,000.

Here, the weight average molecular weight is defined as the polystyreneequivalent by gel permeation chromatography.

Alkali-soluble resins (E) in the invention may be used in combination oftwo kinds or more.

The use amount of alkali-soluble resins is from 40 to 97 mass % based onthe total solids content of the photosensitive composition, andpreferably from 60 to 90 mass %.

-   [6] (F) An acid crosslinking agent capable of crosslinking with the    alkali-soluble resin by the action of an acid (hereinafter also    referred to as “component (F)” or “a crosslinking agent”):

A crosslinking agent is used in the negative photosensitive compositionof the invention.

Every compound capable of crosslinking the resins soluble in an alkalideveloping solution by the action of an acid can be used as crosslinkingagents, but the following (1) to (3) are preferably used.

-   (1) Hydroxymethyl body, alkoxymethyl body and acyloxymethyl body of    phenol derivatives-   (2) Compounds having an N-hydroxymethyl group, an N-alkoxy-methyl    group or an N-acyloxymethyl group-   (3) Compounds having an epoxy group

As the alkoxymethyl groups, those having 6 or less carbon atoms, and asthe acyloxymethyl groups, those having 6 or less carbon atoms arepreferred.

Of these crosslinking agents, particularly preferred compounds are shownbelow.

In the above formulae, L₁ to L₈, which may be the same or different,each represents a hydrogen atom, a hydroxymethyl group, a methoxymethylgroup, an ethoxymethyl group, or an alkyl group having from 1 to 6carbon atoms.

Crosslinking agents are used generally in proportion of from 3 to 70mass % in the solids content of the photosensitive composition, andpreferably from 5 to 50 mass %.

Other Components:

-   [7] (G) A basic compound:

For decreasing the fluctuation of performances during the period of timefrom exposure to heating, it is preferred for the photosensitivecomposition of the invention to contain (G) a basic compound.

As the preferred structures of basic compounds, the structuresrepresented by any of the following formulae (A) to (E) can beexemplified.

In formula (A), R₂₅₀, R₂₅, and R₂₅₂ each represents a hydrogen atom, analkyl group having from 1 to 20 carbon atoms, a cycloalkyl group havingfrom 3 to 20 carbon atoms, or an aryl group having from 6 to 20 carbonatoms, and R₂₅₀ and R₂₅₁ may be bonded to each other to form a ring.These groups may have a substituent, and as the alkyl group andcycloalkyl group having a substituent, an aminoalkyl group having from 1to 20 carbon atoms or an aminocycloalkyl group having from 3 to 20carbon atoms, a hydroxyalkyl group having from 1 to 20 carbon atoms or ahydroxycycloalkyl group having from 3 to 20 carbon atoms are preferred.

These groups may contain an oxygen atom, a sulfur atom or a nitrogenatom in the alkyl chain.

In formula (E), R₂₅₃, R₂₅₄, R₂₅₅ and R₂₅₆ each represents an alkyl grouphaving from 1 to 6 carbon atoms, or a cycloalkyl group having from 3 to6 carbon atoms.

As the preferred examples of basic compounds, guanidine,aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine,aminoalkylmorpholine, and piperidine can be exemplified, and thesecompounds may have a substituent. As further preferred compounds,compounds having an imidazole structure, a diazabicyclo structure, anonium hydroxide structure, an onium carboxylate structure, atrialkylamine structure, an aniline structure, or a pyridine structure,alkylamine derivatives having a hydroxyl group and/or an ether bond, andaniline derivatives having a hydroxyl group and/or an ether bond can beexemplified.

As the compounds having an imidazole structure, imidazole,2,4,5-triphenylimidazole, and benzimidazole can be exemplified. As thecompounds having a diazabicyclo structure,1,4-diazabicyclo[2.2.2]octane, 1,5-diazabicyclo[4.3.0]non-5-ane, and1,8-diazabicyclo[5.4.0]undeca-7-ene can be exemplified. As the compoundshaving an onium hydroxide structure, triarylsulfonium hydroxide,phenacylsulfonium hydroxide, sulfonium hydroxide having a 2-oxoalkylgroup, specifically triphenylsulfonium hydroxide,tris(t-butyl-phenyl)sulfonium hydroxide, bis(t-butylphenyl)iodoniumhydroxide, phenacylthiophenium hydroxide, and 2-oxopropyl-thiopheniumhydroxide can be exemplified. The compounds having an onium carboxylatestructure are compounds having an onium hydroxide structure in which theanionic part is carboxylated, e.g., acetate, adamantane-1-carboxylate,and perfluoroalkyl carboxylate are exemplified. As the compounds havinga trialkylamine structure, tri(n-butyl)amine and tri(n-octyl)amine canbe exemplified. As the aniline compounds, 2,6-diisopropylaniline andN,N-dimethylaniline can be exemplified. As the alkylamine derivativeshaving a hydroxyl group and/or an ether bond, ethanolamine,diethanol-amine, triethanolamine, and tris(methoxyethoxyethyl)amine canbe exemplified. As the aniline derivatives having a hydroxyl groupand/or an ether bond, N,N-bis(hydroxyethyl)-aniline can be exemplified.

These basic compounds are used alone or in combination of two or more.However, when the use amount of component (B) is 0.05 mass % or more, abasic compound may not be used. When a basic compound is used, the useamount of the basic compound is generally from 0.001 to 10 mass % basedon the solids content of the photosensitive composition, and preferablyfrom 0.01 to 5 mass %. For obtaining a sufficient addition effect, theaddition amount is preferably 0.001 mass % or more, and in view ofsensitivity and the developability of a non-exposed area, the additionamount is preferably 10 mass % or less.

-   [8] (H) Surfactant:

It is preferred for the photosensitive composition in the invention tofurther contain a surfactant, and it is more preferred to contain eitherone, or two or more, of fluorine and/or silicon surfactants (a fluorinesurfactant, a silicon surfactant, a surfactant containing both afluorine atom and a silicon atom).

By containing a surfactant, it becomes possible for the photosensitivecomposition in the invention to provide a resist pattern excellent insensitivity and resolution, and low in defects in adhesion anddevelopment in using an exposure light source of 250 nm or lower, inparticular, 220 nm or lower.

These fluorine and/or silicon surfactants are disclosed, e.g., inJP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950,JP-A-63-34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988,JP-A-2002-277862, U.S. Pat. Nos. 5,405,720, 5,360,692, 5,529,881,5,296,330, 5,436,098, 5,576,143, 5,294,511 and 5,824,451. Thecommercially available surfactants shown below can also be used as theyare.

As the commercially available fluorine or silicon surfactants usable inthe invention, e.g., Eftop EF301 and EF303 (manufactured by Shin-AkitaKasei Co., Ltd.), Fluorad FC 430, 431 and 4430 (manufactured by Sumitomo3M Limited), Megafac F171, F173, F176, F189, F113, F110, F177, F120, andR₀₈ (manufactured by Dainippon Ink and Chemicals Inc.), Sarfron S-382,SC 101, 102, 103, 104, 105 and 106 (manufactured by ASAHI GLASS CO.,LTD.), Troy Sol S-366 (manufactured by Troy Chemical Co., Ltd.), GF-300and GF-150 (manufactured by TOAGOSEI CO., LTD.), Sarfron S-393(manufactured by SEIMI CHEMICAL CO., LTD.), Eftop EF121, EF122A, EF122B,RF122C, EF125M, EF135M, EF351, 352, EF801, EF802, and EF601(manufactured by JEMCO INC.), PF636, PF656, PF6320 and PF6520(manufactured by OMNOVA), and FTX-204D, 208G, 218G, 230G, 204D, 208D,212D, 218, and 222D (manufactured by NEOS) are exemplified. In addition,polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co.,Ltd.) can also be used as a silicon surfactant.

In addition to these known surfactants as exemplified above, surfactantsusing polymers having fluoro-aliphatic groups derived fromfluoro-aliphatic compounds manufactured by a telomerization method (alsocalled a telomer method) or an oligomerization method (also called anoligomer method) can be used. The fluoro-aliphatic compounds can besynthesized by the method disclosed in JP-A-2002-90991.

As the polymers having fluoro-aliphatic groups, copolymers of monomershaving fluoro-aliphatic groups and (poly(oxyalkylene)) acrylate and/or(poly(oxyalkylene)) methacrylate are preferred, and they may bedistributed at random or block copolymerized. As the poly(oxyalkylene)groups, a poly(oxyethylene) group, a poly(oxypropylene) group, and apoly(oxybutylene) group are exemplified. Further, the polymers may beunits having alkylenes different in chain length in the same chainlength, such as a block combination of poly(oxyethylene and oxypropyleneand oxyethylene), and a block combination of poly(oxyethylene andoxypropylene). In addition, copolymers of monomers havingfluoro-aliphatic groups and poly(oxyalkylene) acrylate (or methacrylate)may be not only bipolymers but also terpolymers or higher polymersobtained by copolymerization of monomers having different two or morekinds of fluoro-aliphatic groups or different two or more kinds ofpoly(oxyalkylene) acrylates (or methacrylates) at the same time.

For example, as commercially available surfactants, Megafac F178, F470,F473, F475, F476 and F472 (manufactured by Dainippon Ink and ChemicalsInc.) can be exemplified. Further, copolymers of acrylate (ormethacrylate) having a C₆F₁₃ group and poly(oxyalkylene) acrylate (ormethacrylate), and copolymers of acrylate (or methacrylate) having aC₃F₇ group, poly(oxyethylene) acrylate (or methacrylate), andpoly(oxy-propylene) acrylate (or methacrylate) are exemplified.

In the invention, surfactants other than fluorine and/or siliconsurfactants can also be used. Specifically, nonionic surfactants, suchas polyoxyethylene alkyl ethers, e.g., polyoxyethylene lauryl ether,polyoxyethylene stearyl ether, polyoxyethylene cetyl ether,polyoxyethylene oleyl ether, etc., polyoxyethylene alkylallyl ether,e.g., polyoxyethylene octylphenol ether, polyoxyethylene nonylphenolether, etc., polyoxyethylene-polyoxypropylene block copolymers, sorbitanfatty acid esters, e.g., sorbitan monolaurate, sorbitan monopalmitate,sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitantristearate, etc., and polyoxyethylene sorbitan fatty acid esters, e.g.,polyoxy-ethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylene sorbitan tristearate, etc., can beexemplified.

These surfactants may be used alone or may be used in combination ofsome kinds.

The use amount of surfactants is preferably in proportion of from 0.01to 10 mass % to the total amount of the positive resist composition(excluding solvents), and more preferably from 0.1 to 5 mass %.

[9] (I) Organic solvent:

The above components of the photosensitive composition of the inventionare dissolved in a prescribed organic solvent.

As the organic solvents usable in the invention, ethylene dichloride,cyclohexanone, cyclopentanone, 2-heptanone, γ-butyrolactone, methylethyl ketone, ethylene glycol monomethyl ether, ethylene glycolmonoethyl ether, 2-methoxyethyl acetate, ethylene glycol monoethyl etheracetate, propylene glycol monomethyl ether, propylene glycol monomethylether acetate, toluene, ethyl acetate, methyl lactate, ethyl lactate,methyl methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethylpyruvate, propyl pyruvate, N,N-dimethylformamide, dimethyl sulfoxide,N-methylpyrrolidone, and tetrahydrofuran are exemplified.

(Ia) Ketone Solvents:

Solvents containing at least a ketone structure are preferably used inthe invention.

As the solvents containing a ketone structure, chain-like ketonesolvents and cyclic ketone solvents are exemplified, and those havingfrom 5 to 8 carbon atoms are preferred for capable of obtaining goodcoating property.

As the chain-like ketone solvents, e.g., 2-heptanone, methyl ethylketone, methyl isobutyl ketone, etc., are exemplified, and 2-heptanoneis preferred.

As the cyclic ketone solvents, e.g., cyclopentanone,3-methyl-2-cyclopentanone, cyclohexanone, 2-methylcyclo-hexanone,2,6-dimethylcyclohexanone, cycloheptanone, cyclooctanone, isophorone,etc., are exemplified, and cyclohexanone and cycloheptanone arepreferred.

It is preferred that the solvents having a ketone structure are usedalone, or as mixed solvents with other solvents. As the solvents to bemixed (combined use solvents), propylene glycol monoalkyl ethercarboxylate, alkyl lactate, propylene glycol monoalkyl ether, alkylalkoxypropionate, lactone compounds, etc., can be exemplified.

As the propylene glycol monoalkyl ether carboxylate, e.g., propyleneglycol monomethyl ether acetate, propylene glycol monomethyl etherpropionate, propylene glycol monoethyl ether acetate, etc., can beexemplified.

As the alkyl lactate, e.g., methyl lactate, ethyl lactate, etc., can beexemplified.

As the propylene glycol monoalkyl ether, e.g., propylene glycolmonomethyl ether and propylene glycol monoethyl ether, etc., can beexemplified.

As the alkyl alkoxypropionate, e.g., methyl methoxy-propionate, ethylmethoxypropionate, methyl ethoxypropionate, ethyl ethoxypropionate,etc., can be exemplified.

As the lactone compounds, e.g., γ-butyrolactone, etc., can beexemplified.

As preferred combined use solvent, propylene glycol monoalkyl ethercarboxylate, alkyl lactate and propylene glycol monoalkyl ether can beexemplified, and as more preferred combined use solvent, propyleneglycol monomethyl ether acetate can be exemplified.

By the use of mixed solvents of ketone solvents and combined usesolvents, substrate adhesion, developability and DOF are improved.

The ratio of the ketone solvent and the combined use solvent (massratio) is preferably from 10/90 to 95/5, more preferably from 20/80 to80/20, and still more preferably from 30/70 to 70/30.

In view of heightening uniform film thickness and resistance todevelopment failure, high boiling point solvents having a boiling pointof 200° C. or higher, e.g., ethylene carbonate, propylene carbonate,etc., may be mixed.

The addition amount of these high boiling point solvents is generallyfrom 0.1 to 15 mass % in all the solvents, preferably from 0.5 to 10mass %, and more preferably from 1 to 5 mass %.

In the invention, a photosensitive composition having solids contentconcentration of generally from 3 to 25 mass %, preferably from 5 to 22mass %, and more preferably from 5 to 15 mass % is prepared with asingle solvent, preferably two or more solvents.

Other Additives:

If necessary, dyes, plasticizers, surfactants other than the surfactantsof component (H), photosensitizers, and compounds for expediting thedissolution of composition in a developing solution may be further addedto the photosensitive composition in the present invention.

Compounds for expediting dissolution in a developing solution that canbe used in the invention are low molecular weight compounds having amolecular weight of 1,000 or less and having two or more phenolic OHgroups or one or more carboxyl groups. When carboxyl groups arecontained, alicyclic or aliphatic compounds are preferred.

The preferred addition amount of these dissolution acceleratingcompounds is preferably from 2 to 50 mass % based on the resin ofcomponent (C) or the resin of component (E), and more preferably from 5to 30 mass %. The amount is preferably 50 mass % or less in the point ofrestraint of development residue and prevention of pattern deformationin development.

These phenolic compounds having a molecular weight of 1,000 or less canbe easily synthesized with referring to the methods disclosed, e.g., inJP-A-4-122938, JP-A-2-28531, U.S. Pat. No. 4,916,210, and EP 219294.

As the specific examples of the alicyclic or aliphatic compounds havinga carboxyl group, carboxylic acid derivatives having a steroidstructure, e.g., cholic acid, deoxycholic acid, and lithocholic acid,adamantanecarboxylic acid derivatives, adamantanedicarboxylic acid,cyclohexanecarboxylic acid, and cyclohexanedicarboxylic acid areexemplified, but the invention is not restricted to these compounds.

Pattern Forming Method:

The photosensitive composition in the invention is used by dissolvingeach of the above components in a prescribed organic solvent, preferablydissolving in a mixed solvent as described above, and coating thesolution on a prescribed support as follows.

For example, the photosensitive composition is coated on a substratesuch as the one used in the manufacture of precision integrated circuitelement (e.g., silicon/silicon dioxide coating) by an appropriatecoating method with a spinner or a coater, and dried, to thereby form aphotosensitive film.

The photosensitive film is irradiated with actinic ray or radiationthrough a prescribed mask, preferably subjected to baking (heating), andthen development. Thus, a good pattern can be obtained.

At the time of irradiation with actinic ray or radiation, exposure(immersion exposure) may be performed by filling a liquid (an immersionmedium) having higher refractive index than that of air between aphotosensitive film and a lens, by which resolution can be raised.

As actinic rays or radiation, infrared rays, visible rays, ultravioletrays, far ultraviolet rays, X-rays and electron beams can beexemplified, and preferably far ultraviolet rays of wavelengths of 250nm or less, and more preferably 220 mm or less. Specifically, a KrFexcimer laser (248 nm), an ArF excimer laser (193 nm), an F₂ excimerlaser (157 nm), X-rays and electron beams are exemplified, and ArFexcimer lasers, F₂ excimer lasers, EUV (13 nm), and electron beams arepreferred.

Immersion Exposure:

When the photosensitive composition in the invention is subjected toimmersion exposure, it is preferred that the photosensitive compositionis used in a thickness of from 30 to 250 nm in view of the improvementof resolution, and more preferably a thickness of from 30 to 100 nm.Such a desired thickness can be realized by setting the concentration ofsolids content in the photosensitive composition in a proper range andgiving appropriate viscosity to thereby improve the coating property andfilm forming property.

The concentration of all the solids content in the photosensitivecomposition is generally from 1 to 10 mass %, more preferably from 1 to8 mass %, and still more preferably from 1.0 to 6.0 mass %.

When the photosensitive composition in the invention is subjected toimmersion exposure, the photosensitive composition is used by dissolvingeach of the above components in a prescribed organic solvent, preferablyin a mixed solvent as described above, and coating the solution on aprescribed support as follows.

That is, the photosensitive composition is coated on a substrate such asthe one used in the production of precision integrated circuit elements(e.g., silicon/silicon dioxide coating) by an appropriate coating methodwith a spinner or a coater in an arbitrary thickness (generally from 30to 500 nm). After coating, if necessary, a resist film is washed withthe immersion liquid. The washing time is generally from 5 seconds to 5minutes.

Subsequently, the coated resist is dried by spin or bake to form aresist film, and the resist film formed is subjected to exposure(immersion exposure) for pattern formation through a mask via animmersion liquid. For example, exposure is performed in the state offilling an immersion liquid between a resist film and an optical lens.The exposure dose can be optionally set, but is generally from 1 to 100mJ/cm². After exposure, if necessary, the resist film is washed with theimmersion liquid. The washing time is generally from 5 seconds to 5minutes. After that, the resist film is preferably subjected to spinor/and bake, development and rinsing, whereby a good pattern can beobtained. It is preferred to perform bake, and the temperature of bakeis generally from 30 to 300° C. The time from exposure to bake processis preferably shorter from the viewpoint of PED.

The exposure rays here are far ultraviolet rays of wavelengths ofpreferably 250 nm or less, and more preferably 220 nm or less.Specifically, a KrF excimer laser (248 nm), an ArF excimer laser (193nm), an F₂ excimer laser (157 nm), and X-rays are exemplified.

Incidentally, the variation of performances of a resist at the time whensubjected to immersion exposure is thought to be resulting from thecontact of a resist surface with an immersion liquid.

An immersion liquid for use in immersion exposure is described below.

An immersion liquid for use in immersion exposure preferably has atemperature coefficient of refractive index as small as possible so asto be transparent to the exposure wavelength and to hold the distortionof an optical image reflected on the resist at the minimum. Inparticular, when the exposure light source is an ArF excimer laser(wavelength: 193 nm), it is preferred to use water as the immersionliquid for easiness of availability and capable of handling easily, inaddition to the above points.

It is also possible to use a medium having a refractive index of 1.5 ormore for capable of improving the refractive index. The medium may be anaqueous solution or an organic solvent.

When water is used as the immersion liquid, to reduce the surfacetension of water and to increase the surface activity, a trace amount ofadditive (a liquid) that does not dissolve the resist layer on a waferand has a negligible influence on the optical coating of the undersideof a lens element may be added. As such additives, aliphatic alcoholshaving a refractive index almost equal to the refractive index of waterare preferred, specifically methyl alcohol, ethyl alcohol and isopropylalcohol are exemplified. By adding an alcohol having a refractive indexalmost equal to that of water, even if the alcohol component in water isevaporated and the concentration of the content is changed, therefractive index variation of the liquid as a whole can be madeextremely small. On the other hand, when impurities opaque to the lightof 193 nm or substances largely different from water in a refractiveindex are mixed, these substances bring about the distortion of anoptical image reflected on the resist. Accordingly the water to be usedis preferably distilled water. Further, pure water filtered through anion exchange filter may be used.

The electric resistance of water is preferably 18.3 MΩ·cm or higher, andTOC (total organic material concentration) is preferably 20 ppb orlower, and it is preferred that water has been subjected to deaerationtreatment.

It is possible to heighten lithographic performance by increasing therefractive index of an immersion liquid. From such a point of view,additives capable of increasing the refractive index may be added towater, or heavy water (D₂O) may be used in place of water.

A film hardly soluble in an immersion liquid (hereinafter also referredto as “topcoat”) may be provided between a resist film by the positiveresist composition of the invention and an immersion liquid so as not tobring the resist film into direct contact with the immersion liquid. Thenecessary functions required of the topcoat are the aptitude for coatingon the upper layer of a resist, the transparency to radiation, inparticular the transparency to the ray of 193 nm, and the insolubilityin an immersion liquid. It is preferred that the topcoat is not mixedwith a resist and can be coated uniformly on a resist upper layer.

From the viewpoint of the transparency to 193 nm, a polymer notcontaining an aromatic group is preferred as the topcoat. Specifically,hydrocarbon polymers, acrylic ester polymers, polymethacrylic acid,polyacrylic acid, polyvinyl ether, silicon-containing polymers, andfluorine-containing polymers are exemplified. Considering thatimpurities eluting from a topcoat to the immersion liquid contaminatethe optical lens, the residual monomer components of the polymercontained in the topcoat is preferably less.

When the topcoat is peeled off, a developing solution may be used, or aremover may be used separately. As the remover, a solvent low inpenetration into a resist is preferred. In view of capable of performinga peeling process at the same time with the development process of aresist, it is preferred that the topcoat can be peeled off by an alkalideveloping solution. From the viewpoint of performing peeling with analkali developing solution, the topcoat is preferably acidic, but fromthe viewpoint of non-intermixture with the resist, it may be neutral oralkaline.

Resolution increases when there is no difference in the refractiveindexes between the topcoat and the immersion liquid. When water is usedas the immersion liquid in ArF excimer laser (wavelength: 193 nm)exposure, it is preferred that the refractive index of the topcoat forArF immersion exposure is nearer the refractive index of the immersionliquid. For bringing the refractive index of the topcoat nearer to thatof the immersion liquid, it is preferred for the topcoat to contain afluorine atom. Further, from the viewpoint of the transparency andrefractive index, the thickness of the topcoat is preferably thinner.

It is preferred that a topcoat should not be mixed with a resist, andfurther not mixed with an immersion liquid. From this point of view,when water is used as the immersion liquid, the solvent for a topcoat ispreferably hardly soluble in the solvent of the resist and a nonaqueousmedium. Further, when an immersion liquid is an organic solvent, thetopcoat may be aqueous or nonaqueous.

A resist composition in the invention as formed to a resist film has thereceding contact angle of water to the resist film of preferably 65° ormore. Here, the receding contact angle is the angle under normaltemperature and atmospheric pressure. The receding contact angle is thecontact angle of going back at the time when a resist film is inclinedand a droplet begins to drop.

In a development process, a developing solution is used as follows. Asthe alkali developing solution of a resist composition, alkaline aqueoussolutions of inorganic alkalis, e.g., sodium hydroxide, potassiumhydroxide, sodium carbonate, sodium silicate, sodium metasilicate,aqueous ammonia, etc., primary amines, e.g., ethylamine, n-propylamine,etc., secondary amines, e.g., diethylamine, di-n-butylamine, etc.,tertiary amines, e.g., triethylamine, methyldiethylamine, etc., alcoholamines, e.g., dimethylethanolamine, triethanolamine, etc., quaternaryammonium salts, e.g., tetramethylammonium hydroxide, tetraethylammoniumhydroxide, etc., and cyclic amines, e.g., pyrrole, piperidine, etc., canbe used.

An appropriate amount of alcohols and surfactants may be added to thesealkali developing solutions.

The alkali concentration of an alkali developing solution is generallyfrom 0.1 to 20 mass %.

The pH of an alkali developing solution is generally from 10.0 to 15.0.

EXAMPLE

The invention will be described with reference to examples, but theinvention is not limited thereto. Synthesis of Compound (A):

Synthesis Example 1 Synthesis of Compound (A-1)

A mixture comprising 4.0 g (6.91 mmol) of4-hydroxy-phenyldiphenylsulfonium1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonate, 1.71 g (10.37 mmol) of3-bromo-dihydrofuran-2(3H)-one, 2.87 g of potassium carbonate, and 30 mlof acetone was refluxed under nitrogen current for 7 hours. To thereaction mixture were added 200 ml of water and 200 ml of ethyl acetate,the organic layer was washed with water, a saturated sodium chlorideaqueous solution, and water in the order, and the organic layer wasdried with sodium sulfate. The solvent was concentrated, and the residuewas purified by column chromatography (SiO₂, chloroform/methanol: 6/1)to obtain 2.55 g of brown and oily objective compound (A-1).

¹H-NMR (400 MHz, CDCl₃) δ 2.45 (m, 1H), 2.99 (m, 1H), 4.56 (m, 1H), 5.33(t, 1H), 7.41 (d, 2H), 7.63-7.77 (m, 15H)

¹⁹F-NMR (400 MHz, CDCl₃) 6-126 (s, 2F), −122 (s, 2F), −115 (s, 2F), −81(s, 3F)

Synthesis Example 2 Synthesis of Compound (A-34)

A mixture comprising 13.65 g (90.9 mmol) of 3-phenyl-propanoic acid,15.0 g (90.9 mmol) of 3-bromo-dihydrofuran-2(3H)-one, 37.7 g ofpotassium carbonate, and 150 ml of acetone was refluxed under nitrogencurrent for 9 hours. To the reaction mixture were added 200 ml of waterand 400 ml of ethyl acetate, the organic layer was washed with water, asaturated sodium hydrogencarbonate aqueous solution, a saturated sodiumchloride aqueous solution, and water in the order, and the organic layerwas dried with sodium sulfate. The solvent was concentrated to obtain24.3 g of brown and oily tetrahydro-2-oxofuran-3-yl 3-phenylpropanoate.The oily compound (5.00 g) (21.3 mmol), 4.32 g (21.3 mmol) of diphenylsulfoxide, 6 ml of trifluoroacetic anhydride, and 6.7 g (22.3 mmol) of1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonic acid were stirred withice-cooling for 3 hours, and further at room temperature for 2 hours.Chloroform (200 ml) was added to the reaction solution, the organiclayer was washed with water, and the residue was purified by columnchromatography (SiO₂, chloroform/methanol: 10/1) to obtain 8.2 g of oilycompound (A-34).

¹H-NMR (400 MHz, CDCl₃) δ 2.30 (m, 1H), 2.68 (m, 1H), 2.80 (t, 2H), 3.08(t, 2H), 4.28 (m, 1H), 4.47 (m, 1H), 5.43 (t, 1H), 7.56 (d, 2H),7.65-7.70 (m, 15H)

¹⁹F-NMR (400 MHz, CDCl₃) δ-126 (s, 2F), −122 (s, 2F), −115 (s, 2F), −81(s, 3F)

Resin (C):

The structure, molecular weight and degree of molecular weightdispersion of each resin (C) used in Examples are shown below. Thenumber on the right hand of each repeating unit is a molar ratio, andthe rest is the same.

Examples 1 to 19 and Comparative Examples 1 to 5

Preparation of Resist:

A solution having the concentration of solids content of 12 mass % wasprepared by dissolving the components shown in Table 2 below in thesolvent shown in Table 2, and a positive resist solution was prepared byfiltrating the above-prepared solution through a polytetrafluoroethylenefilter or a polyethylene filter having a pore size of 0.1 μm. The thusprepared positive resist solution was evaluated as follows. The resultsobtained are shown in Table 2.

Evaluation of Resist:

Exposure Condition (1)

An antireflection film DUV-42 (manufactured by Brewer Science) wasuniformly coated on a silicone substrate subjected tohexamethyldisilazane treatment in a thickness of 600 Å by a spin coater,and dried on a hot plate at 100° C. for 90 seconds, and then dried byheating at 190° C. for 240 seconds. After that, each positive resistsolution was coated thereon by a spin coater and dried at 120° C. for 90seconds to form a resist film having a thickness of 0.25 μm.

The resist film was subjected to exposure through a mask with an ArFexcimer laser stepper (NA: 0.6, manufactured by ISI Co.), and heated ona hot plate at 120° C. for 90 seconds just after exposure. Further, theresist film was developed with a 2.38 mass % tetramethylammoniumhydroxide aqueous solution at 23° C. for 60 seconds, rinsed with purewater for 30 seconds, and then dried, whereby a line pattern was formed.

Exposure Condition (2)

In condition (2), a resist pattern was formed by immersion exposure withpure water.

An organic antireflection film ARC29A (manufactured by Nissan ChemicalIndustries, Ltd.) was coated on a silicon wafer, and the coated layerwas baked at 205° C. for 60 seconds to form an antireflection filmhaving a thickness of 78 nm. The positive resist solution prepared wascoated on the antireflection film and baked at 120° C. for 60 seconds,whereby a resist film having a thickness of 250 nm was formed. Theobtained wafer was subjected to pattern exposure with an ArF excimerlaser immersion scanner (NA: 0.75). Super pure water of impurities of 5ppb or less was used as the immersion liquid. After that, the resistfilm was heated at 120° C. for 60 seconds, developed with a 2.38 mass %tetramethylammonium hydroxide aqueous solution for 30 seconds, rinsedwith pure water, and then dried by spinning to obtain a resist pattern.

Resist patterns formed by exposure conditions (1) and (2) were evaluatedas follows.

Pattern Profile:

Taking the exposure amount required to reproduce the mask pattern ofline and space of line width 90 nm as the optimal exposure amount, aprofile at the optimal exposure amount was observed with a scanningelectron microscope (SEM).

Line Edge Roughness:

In regard to the edge of the range of 5 μm in the machine direction ofthe line pattern, the distance from the intrinsic base line of the edgewas measured at 50 points with an SEM (S-8840, manufactured by Hitachi,Ltd.), and the standard deviation was found, from which 3σ was computed.The smaller the value, the better is the performance.

TABLE 2 ArF Positive Exposure Exposure Condition Condition Acid (I) (II)Generator Dissolution Line Line Compound Used in Basic SolventInhibiting Edge Edge Ex. (A) Combination Resin Compound Surfactant (massCompound Pattern Roughness Pattern Roughness No. (g) (g) (10 g) (g)(0.03 g) ratio) (g) Profile (nm) Profile (nm) Ex. 1 A-1 (0.3) z38 (0.3)RA-20 PEA/TPA W-4 A1/B1 Rectangle 4.0 Rectangle 4.5 (0.01/0.02) (60/40)Ex. 2 A-1 (0.2) z60 (0.3) RA-20 PEA/DIA W-4 A1/B1 LCB (0.2) Rectangle4.1 Rectangle 3.7 Z38 (0.4) (0.01/0.02) (80/20) Ex. 3 A-3 (0.2) z68(0.4) RA-22 PEA (0.02) W-4 A1/B1 Rectangle 6.4 Rectangle 3.2 (60/40) Ex.4 A-5 (0.3) z78 (0.3) RA-20 DIA (0.02) W-4 A1/B2 Rectangle 5.7 Rectangle3.4 (80/20) Ex. 5 A-7 (0.2) z60 (0.4) RA-24 PEA/DIA W-4 A1/B2 Rectangle6.4 Rectangle 3.7 (0.02/0.02) (80/20) Ex. 6 A-16 (0.3) z34 (0.4) RA-25PEA/DIA W-4 A1/B1 Rectangle 3.4 Rectangle 4.5 (0.01/0.02) (60/40) Ex. 7A-22 (0.3) z66 (0.3) RA-24 PEA/DIA W-4 A1/B1 Rectangle 4.0 Rectangle 2.5(0.02/0.02) (80/20) Ex. 8 A-31 (0.4) z65 (0.4) RA-4 PEA (0.02) W-4 A1/A3Rectangle 4.3 Rectangle 3.4 (60/40) Ex. 9 A-4 (0.2) z63 (0.15) RA-23 PEA(0.02) W-2 A1/B1 LCB (0.3) Rectangle 5.0 Rectangle 2.8 (70/30) Ex. 10A-39 (0.3) z63 (0.3) RA-20 PEA (0.02) W-4 A1/A4 Rectangle 3.0 Rectangle3.4 (60/40) Ex. 11 A-34 (0.2) z38 (0.4) RA-22 PEA (0.02) W-4 A1/B1 LCB(0.1) Rectangle 4.2 Rectangle 4.2 z63 (0.4) (60/40) Ex. 12 A-46 (0.3)z63 (0.3) RA-21 PEA (0.02) W-2 A1/B1 Rectangle 3.9 Rectangle 3.4 (70/30)Ex. 13 A-48 (0.3) z69 (0.5) RA-26 PEA/DIA W-4 A1/B1 LCB (0.2) Rectangle4.7 Rectangle 3.5 (0.01/0.01) (80/20) Ex. 14 A-53 (0.3) z60 (0.3) RA-8PEA (0.03) W-4 A1/A3 Rectangle 3.6 Rectangle 3.7 (60/40) Ex. 15 A-25(0.2) z61 (0.3) RA-21 PEA (0.02) W-1 A1/A4 Rectangle 3.6 Rectangle 4.8(60/40) Ex. 16 A-34 (0.4) z50 (0.4) RA-15 PEA (0.03) W-4 A1/B1 Rectangle3.9 Rectangle 3.3 (80/20) Ex. 17 A-31 (0.4) z60 (0.4) RA-25 TMEA (0.03)W-2 A1/A3 Rectangle 3.7 Rectangle 3.7 (80/20) Ex. 18 A-21 (0.35) z38(0.5) RA-20 DIA (0.02) W-4 A1/B1 Rectangle 4.3 Rectangle 3.6 (80/20) Ex.19 A-34 (0.3) — (—) RA-1 — (—) — A1/B1 Rectangle 4.0 Rectangle 2.8(60/40) Acid Generator Dissolution Comparative Used in Basic SolventInhibiting Exposure Exposure Ex. Compound Combination Resin CompoundSurfactant (mass Compound Condition Condition No. (A) (g) (10 g) (g)(0.03 g) ratio) (g) (I) (II) Comp. — (—) z38 (0.3) RA-1 PEA/DIA W-4A1/B1 Taper 8.0 Taper 9.5 Ex. 1 (0.01/0.02) (60/40) Comp. TPSB (0.3) z38(0.4) RA-20 PEA (0.03) W-4 A1/B1 Taper 9.9 Taper 11.8 Ex. 2 (80/20)Comp. m-TPSB z38 (0.4) RA-19 DIA (0.03) W-1 A1/B1 Taper 10.2 Taper 9.6Ex. 3 (0.3) (70/30) Comp. p-TPSB z38 (0.4) RA-21 PEA (0.03) W-4 A1/B1Taper 10.2 Taper 10.9 Ex. 4 (0.3) (70/30) Comp. TPSPB (0.2) z38 (0.3)RA-20 TMEA (0.03) W-4 A1/B1 LCB (0.2) Taper 10.9 Taper 11.2 Ex. 5(60/40)

The abbreviations common to each table are enumerated together below.

Comparative Compounds:

The abbreviations of comparative compounds used in Comparative Examplesare as follows.

-   TPSB: Triphenylsulfonium pentafluorobenzenesulfonate

-   TPSPB: Triphenylsulfonium perfluorobutanesulfonate

Basic compounds:

-   TPI: 2,4,5-Triphenylimidazole-   TPSA: Triphenylsulfonium acetate-   HEP: N-Hydroxyethylpiperidine-   DIA: 2,6-Diisopropylaniline-   DCMA: Dicyclohexylmethylamine-   TPA: Tripentylamine-   HAP: Hydroxyantipyrine-   TBAH: Tetrabutylammonium hydroxide-   TMEA: Tris(methoxyethoxyethyl)amine-   PEA: N-Phenyldiethanolamine-   TOA: Trioctylamine-   DBN: 1,5-Diazabicyclo[4.3.0]non-5-ane    Surfactants:-   W-1: Megafac F 176 (fluorine surfactant, manufactured by Dainippon    Ink and Chemicals Inc.)-   W-2: Megafac R₀₈ (fluorine/silicon surfactant, manufactured by    Dainippon Ink and Chemicals Inc.)-   W-3: Polysiloxane polymer KP-341 (silicon surfactant, manufactured    by Shin-Etsu Chemical Co., Ltd.)-   W-4: Troy Sol S-366 (manufactured by Troy Chemical Co., Ltd.)    Solvents:-   A1: Propylene glycol monomethyl ether acetate-   A2: 2-Heptanone-   A3: Cyclohexanone-   A4: γ-Butyrolactone-   B1: Propylene glycol monomethyl ether-   B2: Ethyl lactate    Dissolution Inhibiting Compounds:-   LCB: t-Butyl lithocholate

From the results shown in Table 2, it is apparently seen that thephotosensitive compositions in the invention are excellent in patternprofile and line edge roughness in ArF ordinary exposure and ArFimmersion exposure.

Examples 20 to 25 and Comparative Examples 6 to 10

(1) Formation of Lower Resist Layer

FHi-028DD resist (resist for i-ray, manufactured by Fuji Film Olin Co.,Ltd.) was coated on a 6 inch silicon wafer with a spin coater Mark 8(manufactured by Tokyo Electron Limited), baked at 90° C. for 90seconds, whereby a uniform film having a thickness of 0.55 μm wasobtained.

The obtained film was further heated at 200° C. for 3 minutes to obtaina lower resist layer having a thickness of 0.40 μm.

(2) Formation of Upper Resist Layer

A solution having the concentration of solids content of 11 mass % wasprepared by dissolving the components shown in Table 3 below in thesolvent shown in Table 3. The solution was filtrated through a membranefilter having a pore diameter of 0.1 μm, whereby a composition for anupper resist layer was prepared.

The upper resist layer coating composition was coated on the lowerresist layer in the same manner as in the lower layer, and heated at130° C. for 90 seconds, whereby an upper resist layer having a thicknessof 0.20 μm was formed.

Resins S(SI-1) to (SI-5) in Table 3 are as follows.

Molecular Weight (SI-2)

15000 (SI-2)

14500 (SI-3)

 9600 Molecular Weight (SI-4)

 8900 (SI-5)

10800(3) Evaluation of Resist

The thus-obtained wafer was subjected to exposure with ArF ExcimerStepper 9300 (manufactured by ISI Co.) attached with a resolution maskwith varying the exposure amount.

Subsequently, after heating at 120° C. for 90 seconds, the wafer wasdeveloped with a 2.38 mass % tetrahydroammonium hydroxide developingsolution for 60 seconds, rinsed with distilled water and dried to forman upper layer pattern. The pattern profile and line edge roughness ofthe resist were evaluated in the same manner as in Example 1.

The results obtained are shown in Table 3 below.

TABLE 3 Silicon-containing Positive Acid Generator Compound Used inBasic Line Edge Example (A) Combination Resin Compound SurfactantSolvent Pattern Roughness No. (g) (g) (10 g) (g) (0.03 g) (mass ratio)Profile (nm) Ex. 20 A-1 (0.4) z38 (0.4) SI-1 PEA (0.02) W-4 A1/A3(80/20) Rectangle 3.8 Ex. 21 A-5 (0.3) z60 (0.3) SI-1 PEA (0.03) W-1A1/A3 (50/50) Rectangle 3.2 Ex. 22 A-7 (0.3) z38 (0.4) SI-2 PEA (0.02)W-3 A1/A3 (80/20) Rectangle 6.5 Ex. 23 A-39 (0.3) z38 (0.4) SI-3 TPA(0.03) W-4 A1 (100) Rectangle 5.9 Ex. 24 A-31 (0.3) z38 (0.3) SI-4 DIA(0.03) W-4 A1 (100) Rectangle 4.1 Ex. 25 A-34 (0.25) z60 (0.4) SI-5 TMEA(0.03) W-3 A1/A3 (80/20) Rectangle 3.0 Acid Generator Comparative Usedin Basic Line Edge Example Compound Combination Resin CompoundSurfactant Solvent Pattern Roughness No. (g) (g) (10 g) (g) (0.03 g)(mass ratio) Profile (nm) Comp. — (—) z38 (0.4) SI-1 PEA (0.02) W-1 A1(100) Taper 10.5 Ex. 6 Comp. TPSB (0.3) z60 (0.3) SI-2 DIA (0.03) W-4A1/A3 (60/40) Taper 9.9 Ex. 7 Comp. m-TPSB (0.4) z38 (0.4) SI-5 PEA(0.03) W-4 A1/B1 (70/30) Taper 10.1 Ex. 8 Comp. p-TPSB (0.3) z38 (0.3)SI-4 DIA (0.03) W-4 A1/A3 (70/30) Taper 9.1 Ex. 9 Comp. TPSPB (0.3) z66(0.4) SI-4 TPA (0.04) W-1 A1/A3 (60/40) Taper 10.7 Ex. 10

From the results shown in Table 3, it is apparently seen that thephotosensitive compositions in the invention are also excellent inpattern profile and line edge roughness when used as two-layeredresists.

Examples 26 to 31 and Comparative Examples 11 to 15

Preparation of Resist:

A positive resist solution having the concentration of solids content of14 mass % was prepared by dissolving the components shown in Table 4below in the solvent, and filtrating the solution through apolytetrafluoroethylene filter having a pore size of 0.1 μm.

Evaluation of Resist:

The prepared positive resist solution was uniformly coated on a siliconsubstrate having been subjected to hexamethyldisilazane treatment by aspin coater, and dried by heating on a hot plate at 120° C. for 90seconds to form a resist film having a thickness of 0.4 μm.

The resist film was subjected to pattern exposure through a mask forline and space with a KrF excimer laser stepper (NA: 0.63), and heatedon a hot plate at 110° C. for 90 seconds just after exposure. Further,the resist film was developed with a 2.38 mass % tetramethylammoniumhydroxide aqueous solution at 23° C. for 60 seconds, rinsed with purewater for 30 seconds, and then dried, whereby a line pattern was formed.The pattern profile and line edge roughness of the resist were evaluatedin the same manner as in Example 1.

The results obtained are shown in Table 4 below.

TABLE 4 KrF Positive Acid Generator Dissolution Compound Used inInhibiting Line Edge Ex. (A) Combination Resin Basic Compound SurfactantSolvent Compound Pattern Roughness No. (g) (g) (10 g) (g) (0.03 g) (massratio) (g) Profile (nm) Ex. 26 A-1 (0.4) z38 (0.4) R-2 PEA (0.04) W-4A1/B1 (60/40) Rectangle 3.7 Ex. 27 A-5 (0.3) z60 (0.3) R-7 PEA/DIA(0.01/0.02) W-1 A1/B1 (60/40) Rectangle 4.4 Ex. 28 A-7 (0.3) z38 (0.4)R-8 TMEA (0.02) W-4 A1/A3 (60/40) LCB (0.1) Rectangle 3.3 Ex. 29 A-39(0.3) z38 (0.4) R-9 PEA (0.04) W-4 A1/B1 (70/30) Rectangle 3.9 Ex. 30A-31 (0.4) z38 (0.3) R-14 PEA (0.02) W-2 A1/A4 (80/20) Rectangle 3.7 Ex.31 A-34 (0.4) z60 (0.4) R-17 DIA (0.03) W-3 A1/B1 (60/40) Rectangle 4.5Acid Generator Dissolution Comparative Used in Inhibiting Line Edge Ex.Compound Combination Resin Basic Compound Surfactant Solvent CompoundPattern Roughness No. (g) (g) (10 g) (g) (0.03 g) (mass ratio) (g)Profile (nm) Comp. — (—) z38 (0.4) R-2 PEA (0.02) W-4 A1/B1 (60/40)Taper 9.0 Ex. 11 Comp. TPSB (0.3) z60 (0.3) R-7 DIA (0.03) W-4 A1/B1(80/20) Taper 8.4 Ex. 12 Comp. m-TPSB z38 (0.4) R-8 PEA (0.03) W-1 A1/B1(70/30) Taper 12.7 Ex. 13 (0.4) Comp. p-TPSB z38 (0.3) R-9 PEA (0.03)W-4 A1/B1 (70/30) Taper 13.0 Ex. 14 (0.4) Comp. TPSPB (0.3) z66 (0.4)R-14 DIA (0.02) W-1 A1/A3 (60/40) Taper 12.1 Ex. 15

The molar ratio of repeating units and weight average molecular weightof each of resins (R-2), (R-7), (R-8), (R-9), (R-14) and (R-17) used inTable 4 are shown in Table 5 below.

TABLE 5 Weight Molar Ratio of Average Repeating Units Molecular(correspondent from Weight Resin the left in order) (Mw) R-2 60/20/2012,000 R-7 60/30/10 18,000 R-8 60/20/20 12,000 R-9 60/40 13,000 R-1460/15/25 12,000 R-17 80/20 15,000

From the results shown in Table 4, it is apparently seen that thephotosensitive compositions in the invention are also excellent inpattern profile and line edge roughness as the positive resistcompositions in KrF excimer laser exposure.

Examples 32 to 37 and Comparative Examples 16 TO 20

Preparation of Resist:

A negative resist solution having the concentration of solids content of14 mass % was prepared by dissolving the components shown in Table 6below in the solvent, and filtrating the solution through apolytetrafluoroethylene filter having a pore size of 0.1 μm.

Each of the prepared negative resist solutions was evaluated in the samemanner as in Example 26, and the results obtained are shown in Table 6.

TABLE 6 KrF Negative Acid Line Generator Edge Compound Used in Surfac-Crosslinking Rough- Example (A) Combination Resin Basic Compound tantSolvent Agent Pattern ness No. (g) (g) (10 g) (g) (0.03 g) (mass ratio)(g) Profile (nm) Ex. 32 A-1 (0.4) z38 (0.5) P-1 PEA (0.02) W-4 A1/B1(60/40) CL-1 (3) Rectangle 3.7 Ex. 33 A-5 (0.3) z60 (0.3) P-1 DIA (0.03)W-3 A1/B1 (60/40) CL-4 (4) Rectangle 2.5 Ex. 34 A-7 (0.5) z38 (0.4) P-2PEA (0.03) W-1 A1/B1 (80/20) CL-1 (2) Rectangle 3.6 Ex. 35 A-39 (0.3)z38 (0.4) P-2 PEA (0.02) W-2 A1/B1 (70/30) CL-1 (2) Rectangle 3.1 Ex. 36A-31 (0.4) z38 (0.3) P-2 PEA/DIA W-4 A1/A3 (80/20) CL-1 (2) Rectangle4.2 (0.01/0.02) Ex. 37 A-34 (0.3) z60 (0.4) P-3 PEA (0.02) W-4 A1/B1(60/40) CL-3 (2) Rectangle 3.4 Acid Line Generator Edge Comparative Usedin Surfac- Crosslinking Rough- Example Compound Combination Resin BasicCompound tant Solvent Agent Pattern ness No. (g) (g) (10 g) (g) (0.03 g)(mass ratio) (g) Profile (nm) Comp. — (—) z38 (0.4) P-1 HAP (0.02) W-1A1/B1 (60/40) CL-1 (2) Taper 10.5 Ex. 16 Comp. TPSB (0.4) z38 (0.3) P-1DIA (0.03) W-4 A1/B1 (60/40) CL-4 (4) Reverse 8.0 Ex. 17 taper Comp.m-TPSB z38 (0.4) P-2 PEA (0.03) W-4 A1/A4 (80/20) CL-2 (4) Taper 9.9 Ex.18 (0.4) Comp. p-TPSB (0.4) z60 (0.3) P-3 DIA (0.04) W-4 A1/B1 (80/20)CL-1 (2) Taper 10.2 Ex. 19 Comp. TPSPB (0.3) z66 (0.4) P-3 PEA (0.02)W-4 A1/A3 (60/40) CL-5 (2) Taper 10.5 Ex. 20

The structures, molecular weights, and molecular weight distributions ofthe alkali-soluble resins and crosslinking agents in Table 6 are shownbelow.

Mw Mw/Mn P-1

16000 2.30 P-2

12000 1.2 P-3

6000 1.2

VP-5000 (manufactured by Nippon Soda Co., Ltd.)

From the results shown in Table 6, it is apparently seen that thephotosensitive compositions in the invention are also excellent inpattern profile and line edge roughness as the negative resistcompositions in KrF excimer laser exposure.

Examples 38 to 43 and Comparative Examples 21 to 25

Preparation of Resist:

A positive resist solution having the concentration of solids content of12 mass % was prepared by dissolving the components shown in Table 4 inthe solvent, and filtrating the solution through apolytetrafluoroethylene filter having a pore size of 0.1 μm.

Evaluation of Resist:

The prepared positive resist solution was uniformly coated on a siliconsubstrate having been subjected to hexamethyldisilazane treatment by aspin coater, and dried by heating on a hot plate at 120° C. for 60seconds to form a resist film having a thickness of 0.3 μm.

The resist film was irradiated with an electron beam projectionlithographic apparatus (accelerating voltage: 100 keV, manufactured byNikon Corporation), and heated on a hot plate at 110° C. for 90 secondsjust after irradiation. Further, the resist film was developed with a2.38 mass % tetramethyl-ammonium hydroxide aqueous solution at 23° C.for 60 seconds, rinsed with pure water for 30 seconds, and then dried,whereby a line and space pattern was formed. The pattern profile andline edge roughness of the resist were evaluated in the same manner asin Example 1.

The results obtained are shown in Table 7 below.

TABLE 7 EB Positive Line Edge Roughness Pattern Profile (nm) Example No.Example 38 Rectangle 3.5 Example 39 Rectangle 3.4 Example 40 Rectangle3.6 Example 41 Rectangle 3.6 Example 42 Rectangle 3.9 Example 43Rectangle 4.0 Comparative Example No. Comparative Taper 10.2 Example 21Comparative Taper 8.7 Example 22 Comparative Taper 7.5 Example 23Comparative Taper 9.6 Example 24 Comparative Taper 12.1 Example 25 (alittle)

From the results shown in Table 7, it is apparently seen that thephotosensitive compositions in the invention are also excellent inpattern profile and line edge roughness as the positive resistcompositions for electron beam irradiation.

Examples 44 to 49 and Comparative Examples 26 to 30

Preparation of Resist:

A negative resist solution having the concentration of solids content of12 mass % was prepared by dissolving the components shown in Table 6 inthe solvent, and filtrating the solution through apolytetrafluoroethylene filter having a pore size of 0.1 μm.

Evaluation of Resist:

The prepared negative resist solution was uniformly coated on a siliconsubstrate having been subjected to hexamethyldisilazane treatment by aspin coater, and dried by heating on a hot plate at 120° C. for 60seconds to form a resist film having a thickness of 0.3 μm.

The resist film was irradiated with an electron beam projectionlithographic apparatus (accelerating voltage: 100 keV, manufactured byNikon Corporation), and heated on a hot plate at 110° C. for 90 secondsjust after irradiation. Further, the resist film was developed with a2.38 mass % tetramethyl-ammonium hydroxide aqueous solution at 23° C.for 60 seconds, rinsed with pure water for 30 seconds, and then dried,whereby a line and space pattern was formed. The pattern profile andline edge roughness of the resist were evaluated in the same manner asin Example 1.

The results obtained are shown in Table 8 below.

TABLE 8 EB Negative Line Edge Roughness Example No. Pattern Profile (nm)Example 44 Rectangle 4 Example 45 Rectangle 2.9 Example 46 Rectangle 3.4Example 47 Rectangle 3 Example 48 Rectangle 3.4 Example 49 Rectangle 3.7Comparative Taper 10.2 Example 26 Comparative Taper 10.9 Example 27Comparative Taper 10.5 Example 28 Comparative Taper 9.9 Example 29Comparative Taper 11 Example 30

From the results shown in Table 8, it is apparently seen that thephotosensitive compositions in the invention are also excellent inpattern profile and line edge roughness as the negative resistcompositions for electron beam irradiation.

Examples 50 to 55 and Comparative Examples 31 to 35

A positive resist solution having the concentration of solids content of8 mass % was prepared by dissolving the components shown in Table 4 inthe solvent, and filtrating the solution through apolytetrafluoroethylene filter having a pore size of 0.1 μm.

Evaluation of Resist:

The prepared positive resist solution was uniformly coated on a siliconesubstrate having been subjected to hexamethyldisilazane treatment by aspin coater, and dried by heating on a hot plate at 120° C. for 60seconds to form a resist film having a thickness of 0.15 μm. Theobtained resist film was subjected to areal exposure with EUV ray(wavelength: 13 mm) with varying exposure amount 0.5 by 0.5 mJ withinthe range of exposure amount of from 0 to 10.0 mJ, and the resist filmwas further baked at 110° C. for 90 seconds. After that, a dissolvingrate of the resist film at each exposure amount was measured with a2.38% tetramethylammonium hydroxide (TMAH) aqueous solution, and asensitivity curve was obtained. In the sensitivity curve, the exposureamount at the time when the dissolving rate of the resist was saturatedwas taken as sensitivity, and dissolving contrast (γ value) was computedfrom the gradient of the straight line part of the sensitivity curve.The greater the γ value, the better is the dissolving contrast.

The results of evaluations obtained are shown in Table 9 below.

TABLE 9 Extreme Ultraviolet Radiation Sensitivity Example No. (mJ/cm²) γValue Example 50 2.7 17.3 Example 51 2.8 16.2 Example 52 2.9 18.1Example 53 2.2 16.6 Example 54 2.5 17.4 Example 55 2.3 16.8 Comparative5.1 8.2 Example 31 Comparative 5.3 8.8 Example 32 Comparative 5.6 8.6Example 33 Comparative 6.2 9.1 Example 34 Comparative 6.2 10.1 Example35

From the results shown in Table 9, it can be seen that the resistcompositions in the invention are high sensitivity, high contrast andexcellent in the characteristic evaluation by irradiation with EUV raysas compared with comparative compositions.

The invention can provide a photosensitive composition that shows goodline edge roughness and pattern profile, and improved in the contrast ofsensitivity and dissolution in EUV exposure, a pattern-forming methodusing the photosensitive composition, and compounds for use in thephotosensitive composition. The invention can further provide aphotosensitive composition suitable for immersion exposure having goodperformances as described above even in immersion exposure, apattern-forming method using the photosensitive composition, andcompounds for use in the photosensitive composition.

The entire disclosure of each and every foreign patent application fromwhich the benefit of foreign priority has been claimed in the presentapplication is incorporated herein by reference, as if fully set forth.

1. A photosensitive composition, which comprises (A) a sulfonium saltcompound represented by formula (I); and (C) a resin capable ofdecomposing by an action of an acid to increase solubility in an alkalideveloping solution:

wherein A represents an (m+1)-valent linking group, when a plurality ofA's are present, the plurality of A's may be the same or different, andthe plurality of A's may be bonded to each other to form a cyclicstructure; R represents a monovalent organic group, when two R's arepresent, the two R's may be the same or different, and the two R's maybe bonded to each other to form a cyclic structure; L represents alactone ring structure, when a plurality of L's are present, theplurality of L's may be the same or different; X⁻ represents an anion; nrepresents an integer of from 1 to 3; and m represents an integer of 1or 2; and wherein the anion represented by X⁻ in formula (I) is anorganic sulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion (R¹—CO₂⁻), an organic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)(CO—R¹)) or anorganic methidate anion (C⁻(SO₂—R¹)₃), wherein R¹ represents amonovalent organic group, wherein when m is 1, A represents a divalentlinking group for linking S⁺ and L, the divalent linking group beingselected from the group consisting of an arylene group, an alkylenegroup, a cycloalkylene group, an alkenylene group, an ether group, anester group and a group formed by a combination thereof, each of whichmay have a substituent, and when m is 2, A is a group in which anarbitrary hydrogen atom in the divalent linking group selected from thecorresponding case where m is 1 replaced by the other L.
 2. Aphotosensitive composition, which comprises (A) a sulfonium saltcompound represented by formula (I); and (C) a resin capable ofdecomposing by an action of an acid to increase solubility in an alkalideveloping solution:

wherein A represents an (m+1)-valent linking group, when a plurality ofA's are present, the plurality of A's may be the same or different, andthe plurality of A's may be bonded to each other to form a cyclicstructure; R represents a monovalent organic group, when two R's arepresent, the two R's may be the same or different, and the two R's maybe bonded to each other to form a cyclic structure; L represents alactone ring structure, when a plurality of L's are present, theplurality of L's may be the same or different; X⁻ represents an anion; nrepresents an integer of from 1 to 3; and m represents an integer of 1or 2; and wherein the anion represented by X⁻ in formula (I) is anorganic sulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion (R¹—CO₂⁻), an organic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)(CO—R¹)) or anorganic methidate anion (C⁻(SO₂—R¹)₃), wherein R¹ represents amonovalent organic group, and wherein the (m+1)-valent linking grouprepresented by A has an aromatic ring.
 3. A pattern-forming method,which comprises: forming a photosensitive film with a photosensitivecomposition according to claim 1; and exposing and developing thephotosensitive film.
 4. A compound, which is represented by formula (I):

wherein A represents an (m+1)-valent linking group, when a plurality ofA's are present, the plurality of A's may be the same or different, andthe plurality of A's may be bonded to each other to form a cyclicstructure; R represents a cycloalkyl group, an aryl group, an aralkylgroup or an alkenyl group, when two R's are present, the two R's may bethe same or different, and the two R's may be bonded to each other toform a cyclic structure; L represents a lactone ring structure, when aplurality of L's are present, the plurality of L's may be the same ordifferent; X⁻ represents an anion; n represents an integer of from 1 to3; and m represents an integer of 1 or 2; wherein the lactone ringstructure represented by L is represented by any one formulae (LC1-1) to(LC1-16):

wherein Rb₂ represents a substituent; and n₂ represents an integer offrom 0 to 4, provided that when n₂ is 2 or more, a plurality of Rb₂ maybe the same or different, and the plurality of Rb₂ may be bonded to eachother to form a ring, and the lactone ring structure represented by L isbonded to the linking group represented by A on an arbitrary position ofthe ring.
 5. The photosensitive composition according to claim 1, whichfurther comprises: (B) a compound capable of generating an acid uponirradiation with an actinic ray or radiation.
 6. A photosensitivecomposition, which comprises: (A) a sulfonium salt compound representedby formula (I); and (E) a resin soluble in an alkali developingsolution:

wherein A represents an (m+1 )-valent linking group, when a plurality ofA's are present, the plurality of A's may be the same or different, andthe plurality of A's may be bonded to each other to form a cyclicstructure; R represents a monovalent organic group, when two R's arepresent, the two R's may be the same or different, and the two R's maybe bonded to each other to form a cyclic structure; L represents alactone ring structure, when a plurality of L's are present, theplurality of L's may be the same or different; X³¹ represents an anion;n represents an integer of from 1 to 3; and m represents an integer of 1or 2, and wherein the anion represented by X⁻ in formula (I) is anorganic sulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion (R¹—CO₂⁻), an organic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)(CO—R¹)) or anorganic methidate anion (C⁻(SO₂—R¹)₃), wherein R¹ represents amonovalent organic group, and wherein when m is 1, A represents adivalent linking group for linking S⁺ and L, the divalent linking groupbeing selected from the group consisting of an arylene group, analkylene group, a cycloalkylene group, an alkenylene group, an ethergroup, an ester group and a group formed by a combination thereof, eachof which may have a substituent, and when m is 2, A is a group in whichan arbitrary hydrogen atom in the divalent linking group selected fromthe corresponding case where m is 1 is replaced by the other L.
 7. Acompound, which is represented by formula (I):

wherein A represents an (m+1)-valent linking group, when a plurality ofA's are present, the plurality of A's may be the same or different, andthe plurality of A's may be bonded to each other to form a cyclicstructure, provided that when m is 1, A represents a divalent linkinggroup for linking S⁺ and L, the divalent linking group being selectedfrom the group consisting of an arylene group, an alkylene group, acycloalkylene group, an alkenylene group, an ether group, an ester groupand a group formed by a combination thereof; R represents a monovalentorganic group, when two R's are present, the two R's may be the same ordifferent, and the two R's may be bonded to each other to form a cyclicstructure; L represents a lactone ring structure, when a plurality ofL's are present, the plurality of L's may be the same or different; X⁻represents an anion; n represents an integer of from 1 to 3; and mrepresents an integer of 1 or 2; wherein the lactone ring structurerepresented by L is represented by any one formulae (LC1-2) to (LC1-16):

wherein Rb₂ represents a substituent; and n₂ represents an integer offrom 0 to 4, provided that when n₂ is 2 or more, a plurality of Rb₂ maybe the same or different, and the plurality of Rb₂ may be bonded to eachother to form a ring, and the lactone ring structure represented by L isbonded to the linking group represented by A or an arbitrary position ofthe ring.
 8. The compound according to claim 4, wherein the (m+1)-valentlinking group represented by A has an aromatic ring.
 9. The compoundaccording to claim 8, wherein the aromatic ring included in the(m+1)-valent linking group represented by A is a benzene ring, anaphthalene ring, an anthracene ring, a phenanthrene ring, a biphenylenering, a fluorene ring or a pyrene ring.
 10. The compound according toclaim 4, wherein the anion represented by X⁻ in formula (I) is anorganic sulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion (R¹—CO₂⁻), an organic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)(CO—R¹)) or anorganic methidate anion (C⁻(SO₂—R¹)₃), wherein R¹ represents amonovalent organic group.
 11. The compound according to claim 7, whereinthe (m+1)-valent linking group represented by A has an aromatic ring.12. The compound according to claim 11, wherein the aromatic ringincluded in the (m+1)-valent linking group represented by A is a benzenering, a naphthalene ring, an anthracene ring, a phenanthrene ring, abiphenylene ring, a fluorene ring or a pyrene ring.
 13. The compoundaccording to claim 7, wherein the anion represented by X⁻ in formula (I)is an organic sulfonate anion (R¹—SO₃ ⁻), an organic carboxylate anion(R¹—CO₂ ⁻), an organic imidate anion (N⁻(SO₂—R¹)₂, N⁻(SO₂—R¹)(CO—R¹)) oran organic methidate anion (C⁻(SO₂—R¹)₃), wherein R¹ represents amonovalent organic group.
 14. The photosensitive composition accordingto claim 2, wherein the aromatic ring included in the (m+1)-valentlinking group represented by A is a benzene ring, a naphthalene ring, ananthracene ring, a phenanthrene ring, a biphenylene ring, a fluorenering or a pyrene ring.
 15. The photosensitive composition according toclaim 6, wherein the (m+1)-valent linking group represented by A has anaromatic ring.
 16. The photosensitive composition according to claim 15,wherein the aromatic ring included in the (m+1)-valent linking grouprepresented by A is a benzene ring, a naphthalene ring, an anthracenering, a phenanthrene ring, a biphenylene ring, a fluorene ring or apyrene ring.
 17. The photosensitive composition according to claim 1,wherein the lactone ring structure represented by L is represented byany one of formulae (LC1-1) to (LC1-16):

wherein Rb₂ represents a substituent; and n₂ represents an integer offrom 0 to 4, provided that when n₂ is 2 or more, a plurality of Rb₂ maybe the same or different, and the plurality of Rb₂ may be bonded to eachother to form a ring, and the lactone ring structure represented by L isbonded to the linking group represented by A on an arbitrary position ofthe ring.
 18. The photosensitive composition according to claim 6,wherein the lactone ring structure represented by L is represented byany one of formulae (LC1-1) to (LC1-16):

wherein Rb₂ represents a substituent; and n₂ represents an integer offrom 0 to 4, provided that when n₂ is 2 or more, a plurality of Rb₂ maybe the same or different, and the plurality of Rb₂ may be bonded to eachother to form a ring, and the lactone ring structure represented by L isbonded to the linking group represented by A on an arbitrary position ofthe ring.
 19. A pattern-forming method, which comprises: forming aphotosensitive film with a photosensitive composition according to claim1; exposing the photosensitive film through an immersion liquid so as toform an exposed photosensitive film; and developing the exposedphotosensitive film.
 20. A pattern-forming method, which comprises:forming a photosensitive film with a photosensitive compositionaccording to claim 6; exposing the photosensitive film through animmersion liquid so as to form an exposed photosensitive film; anddeveloping the exposed photosensitive film.
 21. A pattern-formingmethod, which comprises: forming a photosensitive film with aphotosensitive composition according to claim 6; and exposing anddeveloping the photosensitive film.
 22. The photosensitive compositionaccording to claim 1, wherein the resin (C) contains a repeating unithaving a group having a lactone structure.
 23. The photosensitivecomposition according to claim 22, wherein the repeating unit having agroup having a lactone structure is a repeating unit represented byformula (AI):

wherein Rb_(o) represents a hydrogen atom, a halogen atom or an alkylgroup having 1 to 4 carbon atoms; Ab represents a single bond, analkylene group, a divalent linking group having a monocyclic orpolycyclic alicyclic hydrocarbon structure, an ether group, an estergroup, a carbonyl group, a carboxyl group or a divalent linking groupcombining these groups; and V represents a group having a lactonestructure represented by any one of formulas (LC 1-1) to (LC1-16):

wherein Rb₂ represents a substituent; and n₂ represents an integer offrom 0 to 4, provided that when n₂ is 2 or more, a plurality of Rb₂ maybe same or different, and the plurality of Rb₂ may be bonded to eachother to form a ring.
 24. The photosensitive composition according toclaim 1, wherein the (m+1)-valent linking group represented by A has anaromatic ring.
 25. The photosensitive composition according to claim 24,wherein the aromatic ring included in the (m+1)-valent inking grouprepresented by A is a benzene ring.
 26. The photosensitive compositionaccording to claim 16, wherein the aromatic ring included in the(m+1)-valent linking group represented by A is a benzene ring.